Abbasid Caliphate

History

Abbasid Revolution (747–750)

The Abbasid caliphs descended from Abbas ibn Abd al-Muttalib, one of the youngest uncles of Muhammad and of the same Banu Hashim clan. This family relation to Muhammad made them appealing to those who were discontented with the rule of the Umayyad caliphs (661–750), who did not descend from the same family. Over the course of their rule, the Umayyads even suppressed several rebellions that attempted to bring other members of Muhammad's family to power. One of the claims that the Abbasids made in the early years of their political movement was that Abu Hashim, the son of Muhammad ibn al-Hanafiyya and grandson of Ali, had formally transferred the Imamate (imāmah) to Muhammad ibn Ali (the great-grandson of Abbas) and thus to the Abbasid family. Muhammad ibn Ali began to campaign in Persia for the return of power to the family of Muhammad, the Hashemites, which may have started during the reign of Umar II. Later, after they had attained power and needed to broaden their support among Muslims, the Abbasids supplemented this claim with other claims to justify their legitimacy.

The Abbasids also distinguished themselves from the Umayyads by attacking their moral character and administration in general. The Abbasids also appealed to non-Arab Muslims, known as mawali, who remained outside the kinship-based society of the Arabs and were perceived as a lower class within the Umayyad empire. The eventual launching point of the revolution was Khurasan (roughly northeastern Iran), a strategic province that was distant from the caliphate's centres of power and had enjoyed a degree of autonomy and local identity since the pre-Islamic Sasanian period. Despite being on the frontier of the Islamic world, it encompassed a relatively large Muslim population made up of both Arab settlers and local converts who were relatively well-integrated with each other. This population resented Umayyad rule, which was seen as foreign and oppressive, and local political tensions had simmered for years. According to Ira Lapidus, "The Abbasid revolt was supported largely by Arabs, mainly the aggrieved settlers of Merv with the addition of the Yemeni faction and their Mawali".

Support for the Abbasids spread through Khurasan during the 740s. In 744 or 745, some of its local leaders, including Qahtaba ibn Shabib, traveled to Mecca for the hajj pilgrimage and met there with the head of the Abbasid family, Ibrahim al-Imam (fourth in descent from Abbas). They pledged allegiance to Ibrahim and returned to Khurasan accompanied by one of Ibrahim's freedmen, a Persian known as Abu Muslim.

Establishment and consolidation (750–775)

Al-Saffah's reign (r. 750–754) was spent consolidating Abbasid rule over the Muslim community. In addition to the caliph himself, most of the real power at this time was in the hands of a triumvirate including the revolutionary leader Abu Muslim, al-Saffah's older brother Abu Ja'far (the future caliph al-Mansur) and al-Saffah's uncle Abdallah ibn Ali (the commander at the battle at the Great Zab).

Soon after the victory of 750, Abu Muslim sent forces to Central Asia to confront an army from Tang China led by Gao Xianzhi. Gao Xianzhi and his army were defeated in 751 at the Battle of Talas, near present-day Tashkent, by the Abbasid army under Ziyad ibn Salih. This defeat marked the end of Tang influence in Transoxiana and halted Tang westward expansion. The Abbasids then consolidated their rule in Transoxania. Elsewhere, the Abbasids focused on putting down numerous rebellions in Syria and Iraq. The Byzantines conducted raids during these early distractions.

One of the first major changes effected by Abbasid rule was the move of the caliphate's center of power from Syria to Iraq. This was closer to the Persian mawali support base of the Abbasids and the move addressed their demand for reduced Arab dominance in the empire. However, no definitive capital was yet selected. In these early Abbasid years, Kufa generally served as the administrative capital, but the caliphs were wary of the Alid sympathies in the city and did not always reside here. In 752, al-Saffah built a new city called al-Hashimiyya, at an uncertain location, most likely near Kufa. Later that same year, he moved to Anbar, where he built a new settlement for his Khurasani soldiers and a palace for himself.

It was al-Saffah's successor, Abu Ja'far al-Mansur (r. 754–775) who firmly consolidated Abbasid rule and faced down internal challenges. His uncle, Abdallah ibn Ali, the victor over the Umayyads at the Battle of the Zab, was the most serious potential rival for leadership and al-Mansur sent Abu Muslim, the Khurasani revolutionary commander, against him in 754. After Abu Muslim successfully defeated him, al-Mansur then turned to eliminate Abu Muslim himself. He arranged to have him arrested and executed in 755.

On the western frontier, the Abbasids were unable to re-assert caliphal control over the western and central Maghreb, which the Umayyads had lost in the 740s. One member of the Umayyad dynasty, Abd al-Rahman, also managed to escape the purge of his family and established independent rule in al-Andalus (present-day Spain and Portugal) in 756, founding the Umayyad emirate of Córdoba.

Golden age (775–861)

The Abbasid leadership had to work hard in the last half of the 8th century (750–800) under several competent caliphs and their viziers to usher in the administrative changes needed to keep order of the political challenges created by the far-flung nature of the empire, and the limited communication across it. It was also during this early period of the dynasty, in particular during the rule of al-Mansur, Harun al-Rashid, and al-Ma'mun, that its reputation and power were created.

The position of wazir (vizier) developed in this period. It was initially akin to a secretary, but under the tenure of the Barmakids, an Iranian family close to the Abbasids, the position became powerful and Harun al-Rashid delegated state affairs to them for many years. This resulted in a more ceremonial role for many Abbasid caliphs compared with caliphal rule under the Umayyads; the viziers began to exert greater influence, and the role of the caliph's aristocracy was slowly replaced by a Barmakid bureaucracy. At the western end of the empire, Harun al-Rashid agreed to grant the province of Ifriqiya (centered in present-day Tunisia) as a hereditary emirate to Ibrahim ibn al-Aghlab, who founded the Aghlabid dynasty there.

Under Harun al-Rashid's reign (r. 786–809), the Abbasid Empire reached its peak. His father, al-Mahdi (r. 775–785), restarted the fighting with the Byzantines, and his sons continued the conflict until Empress Irene pushed for peace. After several years of peace, Nikephoros I broke the treaty, then fended off multiple incursions during the first decade of the 9th century. These Abbasid attacks pushed into the Taurus Mountains, culminating with a victory at the Battle of Krasos and the massive invasion of 806, led by al-Rashid himself. Harun al-Rashid's navy also proved successful, taking Cyprus. Al-Rashid then focused on the rebellion of Rafi ibn al-Layth in Khurasan and died while there.

Domestically, al-Rashid pursued policies similar to those of his father al-Mahdi. He released many of the Umayyads and Alids his brother al-Hadi (r. 785–786) had imprisoned and declared amnesty for all political groups of the Quraysh. While Baghdad remained the official capital, al-Rashid chose to reside in Raqqa from 796 until the end of his reign. In 802, he established an unusual succession plan which decreed that his son al-Amin would inherit the title of Caliph and have control of Iraq and the western empire while his other son al-Ma'mun would rule Khurasan and most eastern parts of the empire. In 803, he turned on and imprisoned or killed most of the Barmakids, who had wielded administrative power on his behalf. The reasons for this sudden and ruthless move remain unclear and have been the subject of much discussion by contemporary writers and later historians.

Political fragmentation (861–945)

From the ninth century onward, the Abbasids found they could no longer keep together a centralized polity from Baghdad, which had grown larger than that of Rome. As mentioned, Harun al-Rashid had already granted the province of Ifriqiya to the Aghlabids, who ruled this region as an autonomous vassal state until its fall to the Fatimids in 909. In al-Ma'mun's reign, Tahir ibn Husayn (al-Ma'mun's general in the civil war) was appointed viceroy of Iran and most of the eastern regions of the empire from 821 onward. His descendants, the Tahirids, continued to govern in this position with significant autonomy until 873, although they remained loyal to the caliph and used only the title of amir. From their capital at Nishapur, they were important patrons of Arabic literature and Sunni religious scholarship, in addition to making major improvements to agriculture. In Transoxiana, the Persian Samanids of Bukhara and Samarkand ruled as local governors, initially under the Tahirids. They oversaw the development of the region's cities into major trade centers, profiting from long-distance trade between China, Central Asia, Eastern Europe, and the Middle East.

The reign of al-Mutawakkil (r. 847–861) was characterized by the caliph's extravagant spending, his attempts to further consolidate power within the state, and his replacement of the Mihna policy with support for more orthodox Sunni scholars, in particular the Hanbali school. In 853, the Byzantines sacked Damietta in Egypt, and the caliph responded by sending troops into Anatolia, who sacked and marauded until they were eventually annihilated in 863.

Al-Mutawakkil's lifestyle and spending weakened his support among the military. In 861, he was murdered at a party by a group of Turkish soldiers. This was the first time the Abbasid military intervened so directly and violently at court and it set a precedent for further coups. The following period, sometimes known as the "Anarchy at Samarra" (861–870), saw four different caliphs come and go. While they each attempted to reassert their authority, they were at the mercy of military and political factions. Tax collection lapsed and, along with al-Mutawakkil's previous spending, this left the state short on funds, which exacerbated the infighting. In 865, the Turkish soldiers of Samarra even besieged Baghdad to overthrow the caliph al-Musta'in and, when the city fell the following year, they replaced him with al-Mu'tazz. The latter was overthrown by the same faction in 869 and replaced by al-Muhtadi, who was similarly overthrown in 870. Al-Muhtadi was succeeded by al-Mu'tamid, who was finally able to restore some order, in large part thanks to the help of his brother al-Muwaffaq, who kept the military under control and ran most government affairs. The restoration was hampered by the Zanj rebellion, which erupted in 869 and threatened the center of Abbasid control in Iraq. This major threat was not brought under control until a determined campaign was launched in 879.

Buyid and Seljuq control (945–1118)

Despite the power of the Buyid amirs, the Abbasids retained a highly ritualized court in Baghdad, as described by the Buyid bureaucrat Hilal al-Sabi', and they retained a certain influence over Baghdad as well as religious life. As Buyid power waned with the rule of Baha' al-Daula, the caliphate was able to regain some measure of strength. The caliph al-Qadir, for example, led the ideological struggle against the Shia with writings such as the Baghdad Manifesto. The caliphs kept order in Baghdad itself, attempting to prevent the outbreak of fitnas in the capital, often contending with the ayyarun.

With the Buyid dynasty on the wane, a vacuum was created that was eventually filled by the dynasty of Oghuz Turks known as the Seljuqs. By 1055, the Seljuqs had wrested control from the Buyids and Abbasids, and took temporal power. When the amir and former slave Basasiri took up the Shia Fatimid banner in Baghdad in 1056–57, the caliph al-Qa'im was unable to defeat him without outside help. Toghril Beg, the Seljuq sultan, restored Baghdad to Sunni rule and took Iraq for his dynasty.

Once again, the Abbasids were forced to deal with a military power that they could not match, though the Abbasid caliph remained the titular head of the Islamic community. The succeeding sultans Alp Arslan and Malikshah, as well as their vizier Nizam al-Mulk, took up residence in Persia, but held power over the Abbasids in Baghdad. When the dynasty began to weaken in the 12th century, the Abbasids gained greater independence once again.

Revival of caliphal state (1118–1258)

Caliph al-Mustarshid (r. 1118–1135) was the first caliph to build an army and to lead it in battle since the 10th century. He recruited Kurdish and Arab Bedouin tribes and re-fortified Baghdad. His first concern was not the Seljuks but the Mazyadids of Hilla in central Iraq, whom he met in battle in 1123. His bid for independence was ultimately unsuccessful, as he was defeated by a Seljuk army in 1135 and assassinated soon after.

Under al-Muqtafi (r. 1136–1160), a new caliphal state began to emerge with the help of his vizier Ibn Hubayra. Ibn Hubayra concentrated on reasserting authority in Iraq while the Seljuk Empire deteriorated. The Abbasids successfully defended Baghdad against the Seljuqs in the siege of 1157 and then conquered their Mazyadid enemies in Hilla in 1162. By the end of al-Muqtafi's reign, Baghdad controlled a state stretching from Basra in the south to the edges of Mosul in the north. After over two hundred years of Abbasid subjection to foreign dynasties, Caliph al-Mustanjid (r. 1160–1170) formally declared independence from the Seljuk sultans in 1165, when he dropped their names from Abbasid coinage. Initially, the caliphs were still vulnerable to the power of the viziers, but al-Mustadi (r. 1170–1180) was able to further rally some support from the Baghdad public as well as symbolic support abroad from the Ayyubid sultan Saladin and the Rum Seljuk sultan Kilij Arslan II.

The long reign of Caliph al-Nasir (r. 1180–1225) marked a definitive shift in late Abbasid power. He reinvigorated public displays of caliphal prestige, removed officials who were too powerful, engaged in diplomacy with regions beyond Iraq, and extended his control over former Seljuk territories in western Iran — including Isfahan, Hamadan, Qazvin and Zanjan. He sought to build up his influence among Muslim rulers abroad largely through the Sufi-inspired futuwwa brotherhood that he headed. Under caliph al-Mustansir (r. 1226–1242), the Abbasid state achieved significant stability and many of the same policies continued. He built the Mustansiriyya Madrasa, inaugurated in 1234, the first madrasa to teach all four Sunni maddhabs (schools of jurisprudence) and the first madrasa commissioned by an Abbasid caliph.

Mongol invasion and end

In 1206, Genghis Khan established a powerful dynasty among the Mongols of Central Asia. During the 13th century, this Mongol Empire conquered most of the Eurasian land mass, including both China in the east and much of the old Islamic caliphate and the Kievan Rus' in the west. In 1252, Hulagu Khan, a grandson of Genghis Khan and brother of the new Mongol ruler, Möngke Khan, was placed in charge of a new western campaign to the Middle East that would culminate in the conquest of Baghdad in 1258.

In the years leading up the Mongol invasion, Baghdad's strength was sapped by political rivalries, sectarian tensions between Sunnis and Shias, and damaging floods. In 1257, after destroying the Assassins in Iran, Hulagu wrote to the Abbasid caliph, al-Musta'sim, demanding his submission. The caliph refused, with Hulagu's status as a non-Muslim (unlike the earlier Buyids and Seljuks) likely a factor. There followed months of diplomacy, during which the Mongols may have been informed of Baghdad's weakness by correspondence with the caliph's vizier, Ibn al-Alqami, a Shia who was later accused of colluding with them.

The Mongols began their siege of the city on 29 January 1258. On 10 February, al-Musta'sim agreed to meet with Hulagu, who demanded that the caliph order the defenders to stand down and come out of the city in exchange for mercy. The caliph complied, but the Mongols slaughtered the population and then began the sack of the city on 13 February. Contemporary accounts describe destruction, looting, rape, and killing on a massive scale over many days, with hundreds of thousands killed and the city reduced to near-empty ruins, though some, like the Christian and Shia communities, were spared. The Mongols feared rumours that a supernatural disaster would strike if the blood of al-Musta'sim, a direct descendant of Muhammad's uncle and part of a dynasty that had reigned for five centuries, was spilled. As a precaution and in accordance with a Mongol taboo against spilling royal blood, Hulagu had al-Musta'sim wrapped in a carpet and trampled to death by horses on 20 February 1258. The caliph's immediate family was also executed, with the lone exceptions of his youngest son who was sent to Mongolia and a daughter who became a slave in the harem of Hulagu.

The fall of Baghdad marked the effective end of the Abbasid Caliphate. It made a deep impression on contemporary and later writers both inside and outside the Muslim world, some of whom created legendary stories about the last caliph's demise. It is also traditionally seen as the approximate end to the "classical age" or "golden age" of Islamic civilization. The events brought profound geopolitical changes to the traditional lands of the Islamic caliphate, with Iraq, Iran, and most of the eastern lands falling under Mongol control while other Muslim rulers retained the lands to the west. Mongol expansion further west was eventually halted by the Mamluks of Egypt at the Battle of Ain Jalut in 1260, followed by the conflict between the Ilkhanids (Hulagu and his successors) and their Golden Horde rivals, which diverted Mongol attention.

Culture

Islamic Golden Age

The Abbasid historical period lasting to the Mongol conquest of Baghdad in 1258 CE is considered the Islamic Golden Age. The Islamic Golden Age was inaugurated by the middle of the 8th century by the ascension of the Abbasid Caliphate and the transfer of the capital from Damascus to Baghdad. The Abbasids were influenced by the Qur'anic injunctions and hadith, such as "the ink of a scholar is more holy than the blood of a martyr", stressing the value of knowledge. During this period the Muslim world became an intellectual center for science, philosophy, medicine and education as the Abbasids championed the cause of knowledge and established the House of Wisdom in Baghdad, where both Muslim and non-Muslim scholars sought to translate and gather all the world's knowledge into Arabic. Many classic works of antiquity that would otherwise have been lost were translated into Arabic and Persian and later in turn translated into Turkish, Hebrew and Latin. During this period the Muslim world was a cauldron of cultures which collected, synthesized and significantly advanced the knowledge gained from the Roman, Chinese, Indian, Persian, Egyptian, North African, Ancient Greek and Medieval Greek civilizations. According to Huff, "[i]n virtually every field of endeavor—in astronomy, alchemy, mathematics, medicine, optics and so forth—the Caliphate's scientists were in the forefront of scientific advance."

Literature

Abbasid literary culture in Iraq reflects long-term Mesopotamian narrative continuities, particularly traditions centered on heroic figures and on barriers separating chaos and order. Core motifs associated with the Epic of Gilgamesh, mediated through the Alexander Romance, including journeys to the world's limits and the containment of chaos, persisted across religious and political change and continued to circulate in late antique Iraq. The Babylonian Talmud, composed by Iraq-based rabbis, preserves parallel traditions concerning Gog and Magog and the imagined edges of the world that confine agents of chaos. Together, these traditions situate elements of Abbasid literature within a Mesopotamian narrative continuum.

The best-known fiction from the Islamic world is One Thousand and One Nights, a collection of fantastical folk tales, legends and parables compiled primarily during the Abbasid era. The collection is recorded as having originated from an Arabic translation of a Sassanian-era Persian prototype, with likely origins in Indian literary traditions. Stories from Arabic, Persian, Mesopotamian, and Egyptian folklore and literature were later incorporated. The epic is believed to have taken shape in the 10th century and reached its final form by the 14th century; the number and type of tales have varied from one manuscript to another. All Arabian fantasy tales were often called "Arabian Nights" when translated into English, regardless of whether they appeared in The Book of One Thousand and One Nights. This epic has been influential in the West since it was translated in the 18th century, first by Antoine Galland. Many imitations were written, especially in France. Various characters from this epic have themselves become cultural icons in Western culture, such as Aladdin, Sinbad and Ali Baba.

A famous example of Islamic poetry on romance was Layla and Majnun, an originally Arabic story which was further developed by Iranian, Azerbaijani and other poets in the Persian, Azerbaijani, and Turkish languages. It is a tragic story of undying love much like the later Romeo and Juliet.

Arabic poetry reached its greatest height in the Abbasid era, especially before the loss of central authority and the rise of the Persianate dynasties. Writers like Abu Tammam and Abu Nuwas were closely connected to the caliphal court in Baghdad during the early 9th century, while others such as al-Mutanabbi received their patronage from regional courts.

Philosophy

One of the common definitions for "Islamic philosophy" is "the style of philosophy produced within the framework of Islamic culture". Islamic philosophy, in this definition is neither necessarily concerned with religious issues, nor is exclusively produced by Muslims. Their works on Aristotle were a key step in the transmission of learning from ancient Greeks to the Islamic world and the West. They often corrected the philosopher, encouraging a lively debate in the spirit of ijtihad. They also wrote influential original philosophical works, and their thinking was incorporated into Christian philosophy during the Middle Ages, notably by Thomas Aquinas.

Three speculative thinkers, al-Kindi, al-Farabi, and Avicenna, combined Aristotelianism and Neoplatonism with other ideas introduced through Islam, and Avicennism was later established as a result. Other influential Abbasid philosophers include al-Jahiz, and Ibn al-Haytham (Alhacen).

Architecture

As power shifted from the Umayyads to the Abbasids, the architectural styles changed also, from Greco-Roman tradition (which features elements of Hellenistic and Roman representative style) to Eastern tradition which retained their independent architectural traditions from Mesopotamia and Persia.

A defining characteristic of Abbasid architecture in Iraq was the extensive use of stucco and plaster decoration, particularly in interior spaces. The limited availability of high-quality building stone in Abbasid Iraq contributed to the widespread use of stucco and other malleable materials, which were well suited to repetitive and abstract ornamental decoration. At Samarra, these conditions enabled the emergence of a standardized decorative vocabulary that departed from Late Antique naturalism and proved influential well beyond Iraq. Color also played an important role, particularly the use of blue pigments to enhance stucco and painted surfaces, intensifying abstraction and, in some contexts, carrying protective or apotropaic associations.

The Abbasid architecture was particularly influenced by Sasanian architecture, which in turn featured elements present since ancient Mesopotamia. The Christian styles evolved into a style based more on the Sasanian Empire, utilizing mud bricks and baked bricks with carved stucco. Other architectural innovations and styles were few, such as the four-centered arch, and a dome erected on squinches. Unfortunately, much was lost due to the ephemeral nature of the stucco and luster tiles.

Another major development was the creation or vast enlargement of cities as they were turned into the capital of the empire, beginning with the creation of Baghdad in 762, which was planned as a walled city with four gates, and a mosque and palace in the center. Al-Mansur, who was responsible for the creation of Baghdad, also planned the city of Raqqa, along the Euphrates. Finally, in 836, al-Mu'tasim moved the capital to a new site that he created along the Tigris, called Samarra. This city saw 60 years of work, with race-courses and game preserves to add to the atmosphere. Due to the dry remote nature of the environment, some of the palaces built in this era were isolated havens. Al-Ukhaidir Fortress is a fine example of this type of building, which has stables, living quarters, and a mosque, all surrounding inner courtyards. Iraq only has one surviving mausoleum from this era, in Samarra: an octagonal domed structure known as the Qubbat al-Sulaibiyya, which is the first known monumental tomb in Islamic architecture and may be the final resting place of al-Muntasir.

Arts

The establishment of Abbasid power based in Iraq, rather than Syria, resulted in a cultural and artistic development influenced not only by the Mediterranean and Middle Eastern traditions but also by connections further afield with India, Central Asia, and China. The importation of Chinese ceramics elicited local imitations but also stirred innovations in local production. Abbasid ceramics became a more important art form with greater emphasis on decoration. A major innovation was the emergence of monochrome and polychrome lustreware, a technical achievement that had an important impact on the wider development of Islamic ceramics. Glassware also became a more important art form and was likely the origin of the lustre technique that was introduced into ceramics. Few textiles have survived but the production of tiraz, textiles with royal inscriptions, is well attested.

Another major art form was calligraphy and manuscript production. During the Abbasid period, Arabic calligraphy evolved into a more refined discipline. Rounded Kufic script was typical and became increasingly stylized. Parchment only allowed for a few lines of script, but from the late 8th century onward paper began to be produced. Qur'ans are the main type of book to have survived from this period.

Science and technology

Science

A number of medieval thinkers and scientists living under Islamic rule played a role in transmitting Islamic science to the Christian West. In addition, the period saw the recovery of much of the Alexandrian mathematical, geometric and astronomical knowledge, such as that of Euclid and Claudius Ptolemy. These recovered mathematical methods were later enhanced and developed by other Islamic scholars, notably by Persian scientists Al-Biruni and Abu Nasr Mansur.

Christians (particularly Nestorian Christians) contributed to the Arab Islamic Civilization during the Umayyads and the Abbasids by translating works of Greek philosophers to Syriac and afterwards to Arabic. Nestorians played a prominent role in the formation of Arab culture, with the Academy of Gondishapur being prominent in the late Sassanid, Umayyad and early Abbasid periods. Notably, eight generations of the Nestorian Bukhtishu family served as private doctors to caliphs and sultans between the eighth and eleventh centuries.

Algebra was significantly developed by Persian scientist Muhammad ibn Mūsā al-Khwārizmī during this time in his landmark text, Kitab al-Jabr wa-l-Muqabala, from which the term algebra is derived. He is thus considered to be the father of algebra by some, although the Greek mathematician Diophantus has also been given this title. The terms algorism and algorithm are derived from the name of al-Khwarizmi, who was also responsible for introducing the Arabic numerals and Hindu–Arabic numeral system beyond the Indian subcontinent.

Arab scientist Ibn al-Haytham (Alhazen) developed an early scientific method in his Book of Optics (1021). The most important development of the scientific method was the use of experiments to distinguish between competing scientific theories set within a generally empirical orientation, which began among Muslim scientists. Ibn al-Haytham's empirical proof of the intromission theory of light (that is, that light rays entered the eyes rather than being emitted by them) was particularly important. Ibn al-Haytham was significant in the history of scientific method, particularly in his approach to experimentation, and has been referred to as the "world's first true scientist".

Medicine in medieval Islam was an area of science that advanced particularly during the Abbasids' reign. During the 9th century, Baghdad contained over 800 doctors, and great discoveries in the understanding of anatomy and diseases were made. The clinical distinction between measles and smallpox was described during this time. Famous Persian scientist Ibn Sina (known to the West as Avicenna) produced treatises and works that summarized the vast amount of knowledge that scientists had accumulated, and was very influential through his encyclopedias, The Canon of Medicine and The Book of Healing. The work of him and many others directly influenced the research of European scientists during the Renaissance.

Technology

In technology, the Abbasids adopted papermaking from China. The use of paper spread from China into the caliphate in the 8th century CE, arriving in al-Andalus (Islamic Spain) and then the rest of Europe in the 10th century. It was easier to manufacture than parchment, less likely to crack than papyrus, and could absorb ink, making it ideal for making records and copies of the Qur'an. "Islamic paper makers devised assembly-line methods of hand-copying manuscripts to turn out editions far larger than any available in Europe for centuries." It was from the Abbasids that the rest of the world learned to make paper from linen. The knowledge of gunpowder was also transmitted from China via the caliphate, where the formulas for pure potassium nitrate and an explosive gunpowder effect were first developed.

Advances were made in irrigation and farming, using new technology such as the windmill. Crops such as almonds and citrus fruit were brought to Europe through al-Andalus, and sugar cultivation was gradually adopted by the Europeans. Apart from the Nile, Tigris and Euphrates, navigable rivers were uncommon, so transport by sea was very important. Navigational sciences were highly developed, making use of a rudimentary sextant (known as a kamal). When combined with detailed maps of the period, sailors were able to sail across oceans rather than skirt along the coast. Abbasid sailors were also responsible for reintroducing large three masted merchant vessels to the Mediterranean. The name caravel may derive from an earlier Arab ship known as the qārib. Arab merchants dominated trade in the Indian Ocean until the arrival of the Portuguese in the 16th century. Hormuz was an important center for this trade. There was also a dense network of trade routes in the Mediterranean, along which Muslim countries traded with each other and with European powers such as Venice or Genoa. The Silk Road crossing Central Asia passed through the Abbasid caliphate between China and Europe.

Engineers in the Abbasid caliphate made a number of innovative industrial uses of hydropower, and early industrial uses of tidal power, wind power, and petroleum (notably by distillation into kerosene). The industrial uses of watermills in the Islamic world date back to the 7th century, while horizontal-wheeled and vertical-wheeled water mills were both in widespread use since at least the 9th century. By the time of the Crusades, every province throughout the Islamic world had mills in operation, from al-Andalus and North Africa to the Middle East and Central Asia. These mills performed a variety of agricultural and industrial tasks. Abbasid engineers also developed machines (such as pumps) incorporating crankshafts, employed gears in mills and water-raising machines, and used dams to provide additional power to watermills and water-raising machines. Such advances made it possible for many industrial tasks that were previously driven by manual labour in ancient times to be mechanized and driven by machinery instead in the medieval Islamic world. It has been argued that the industrial use of waterpower had spread from Islamic to Christian Spain, where fulling mills, paper mills, and forge mills were recorded for the first time in Catalonia.

Society

Arabization

While the Abbasids originally gained power by exploiting the social inequalities against non-Arabs in the Umayyad Empire, during Abbasid rule the empire rapidly Arabized, particularly in the Fertile Crescent region (namely Mesopotamia and the Levant) as had begun under Umayyad rule. As knowledge was shared in the Arabic language throughout the empire, many people from different nationalities and religions began to speak Arabic in their everyday lives. Resources from other languages began to be translated into Arabic, and a unique Islamic identity began to form that fused previous cultures with Arab culture, creating a level of civilization and knowledge that was considered a marvel in Europe at the time.

Status of women

In contrast to the earlier era, women in Abbasid society were absent from all arenas of the community's central affairs. While their Muslim forebears led men into battle, started rebellions, and played an active role in community life, as demonstrated in the Hadith literature, Abbasid women were ideally kept in seclusion. Conquests had brought enormous wealth and large numbers of slaves to the Muslim elite. The majority of the slaves were women and children, many of whom had been dependents or harem-members of the defeated Sassanian upper classes. In the wake of the conquests an elite man could potentially own a thousand slaves, and ordinary soldiers could have ten people serving them.

It was narrated from Ibn Abbas that Muhammad said:

There is no man whose two daughters reach the age of puberty and he treats them kindly for the time they are together, but they will gain him admittance to Paradise.

Whoever has three daughters and is patient towards them, and feeds them, gives them to drink, and clothes them from his wealth; they will be a shield for him from the Fire on the Day of Resurrection.

Some slave courtesans (qiyans and jawaris) and princesses produced prestigious and important poetry. Surviving poetry reveals important female figures in the Abbasid world, such as the Sufi mystic Raabi'a al-Adwiyya (714–801 CE), the princess and poet 'Ulayya bint al-Mahdi (777–825 CE), and the singing-girls Shāriyah (c. 815 – c. 870 CE), Fadl Ashsha'ira (d. 871 CE) and Arib al-Ma'muniyya (797–890 CE).

Each wife in the Abbasid harem had an additional home or flat, with her own enslaved staff of eunuchs and maidservants. When a concubine gave birth to a son, she was elevated in rank to umm walad and also received apartments and (slave) servants as a gift.

Treatment of Jews and Christians

The status and treatment of Jews, Christians, and non-Muslims in the Abbasid Caliphate was a complex and continually changing issue. Non-Muslims were called dhimmis. Dhimmis faced some level of discrimination in Abbasid society: they did not have all the privileges of Muslims and had to pay jizya, a tax on non-Muslims. However, as people of the book (non-Muslim monotheists), Jews and Christians were allowed to practice their religion and were not required to convert.

At the level of family and household life, in the multiconfessional society of the early Islamic empire, particularly in Iraq, and also in Syria and western Iran, Syriac Christian sources show that Christian communities developed distinctive responses to shared social norms around marriage and family life under Abbasid rule. Ecclesiastical authorities discouraged practices such as polygamy and sought to regulate interreligious unions, yet ordinary Christians in Iraq and neighboring regions nonetheless participated in both Christian and Islamic marital practices and households across confessional lines. Christian men might take multiple wives or marry non-Christians, and interreligious marriages, especially those involving Muslim husbands and Christian women, were a persistent concern for Christian jurists, who viewed them as threatening communal boundaries.

One of the common aspects of the treatment of the dhimmis is that their treatment depended on who the caliph was at the time. Some Abbasid rulers, like Al-Mutawakkil (822–861 CE) imposed strict restrictions on what dhimmis could wear in public, often yellow garments that distinguished them from Muslims. Other restrictions al-Mutawakkil imposed included limiting the role of the dhimmis in government, seizing dhimmi housing and making it harder for dhimmis to become educated. Most other Abbasid caliphs were not as strict as al-Mutawakkil. During the reign of Al-Mansur (754–775 CE), it was common for Jews and Christians to influence the overall culture in the caliphate, specifically in Baghdad. Jews and Christians did this by participating in scholarly work.

It was common that laws that were imposed against dhimmis during one caliph's rule were either discarded or not practiced during future caliphs' reigns. Al-Mansur and al-Mutawakkil both instituted laws that forbade non-Muslims from participating in public office. Al-Mansur did not follow his own law very closely, bringing dhimmis back to the caliphate's treasury due to the needed expertise of dhimmis in the area of finance. Al-Mutawakkil followed the law banning dhimmis from public office more seriously, although, soon after his reign, many of the laws concerning dhimmis participating in government were completely unobserved or at least less strictly observed. Even Al-Muqtadir (r. 908–932 CE), who held a similar stance as al-Mutawakkil on barring non-Muslims from public office, himself had multiple Christian secretaries, indicating that non-Muslims still had access to many of the most important figures within the caliphate. Past having a casual association or just being a secretary to high-ranking Islamic officials, some of them achieved the second highest office after the caliph: the vizier.

Holidays

There were large feasts on certain days, as the Muslims of the empire celebrated Christian holidays as well as their own. There were two main Islamic feasts: one marked by the end of Ramadan; the other, "the Feast of Sacrifice". The former was especially joyful because children would purchase decorations and sweetmeats; people prepared the best food and bought new clothes. At midmorning, the caliph, wearing Muhammad's thobe, would guide officials, accompanied by armed soldiers to the Great Mosque, where he led prayers. After the prayer, all those in attendance would exchange the best wishes and hug their kin and companions. The festivities lasted for three days. During those limited number of nights, the palaces were lit up and boats on the Tigris hung lights. It was said that Baghdad "glittered 'like a bride'". During the Feast of Sacrifice, sheep were butchered in public arenas and the caliph participated in a large-scale sacrifice in the palace courtyard. Afterward, the meat would be divided and given to the poor.

In addition to these two holidays, Shias celebrated the birthdays of Fatimah and Ali ibn Abi Talib. Matrimonies and births in the royal family were observed by all in the empire. The announcement that one of the caliph's sons could recite the Koran smoothly was greeted by communal jubilation. When Harun developed this holy talent, the people lit torches and decorated the streets with wreaths of flowers, and his father, Al-Mahdi, freed 500 slaves.

Of all the holidays imported from other cultures and religions, the one most celebrated in Baghdad (a city with many Persians) was Nowruz, which celebrated the arrival of spring. In a ceremonial ablution introduced by Persian troops, residents sprinkled themselves with water and ate almond cakes. The palaces of the imperial family were lit up for six days and nights. The Abbasids also celebrated the Persian holiday of Mihraj, which marked the onset of winter (signified with pounding drums), and Sadar, when homes burned incense and the masses would congregate along the Tigris to witness princes and viziers pass by.

Military

The Abbasid army amassed an array of siege equipment, such as catapults, mangonels, battering rams, ladders, grappling irons, and hooks. All such weaponry was operated by military engineers. However, the primary siege weapon was the manjaniq, a type of siege weapon that was comparable to the trebuchet employed in Western medieval times. From the seventh century onward, it had largely replaced torsion artillery. By Harun al-Rashid's time, the Abbasid army employed fire grenades. The Abbasids also utilized field hospitals and ambulances drawn by camels. The cavalry was entirely covered in iron, with helmets. Similar to medieval knights, their only exposed spots were the end of their noses and small openings in front of their eyes. Their foot soldiers were issued spears, swords, and pikes, and (in line with Persian fashion) trained to stand so solidly that, one contemporary wrote "you would have thought them held fast by clamps of bronze". Although the Abbasids never retained a substantial regular army, the caliph could recruit a considerable number of soldiers in a short time when needed from levies. There were also cohorts of regular troops who received steady pay and a special forces unit. At any moment, 125,000 Muslim soldiers could be assembled along the Byzantine frontier, Baghdad, Medina, Damascus, Rayy, and other geostrategic locations in order to quell any unrest.

During the Abbasid revolution, Abu Muslim's Khurasani army, composed largely of Arab settlers disillusioned with Umayyad rule, marched under black banners, forming a powerful force that swept westward in open revolt. In Baghdad there were many Abbasid military leaders who were or said they were of Arab descent. However, it is clear that most of the ranks were of Iranian origin, the vast majority being from Khurasan and Transoxiana, not from western Iran or Azerbaijan. Most of the Khurasani soldiers who brought the Abbasids to power were Arabs. The standing army of the Muslims in Khurasan was overwhelmingly Arab. The unit organization of the Abbasids was designed with the goal of ethnic and racial equality among supporters. When Abu Muslim recruited officers along the Silk Road, he registered them based not on their tribal or ethno-national affiliations but on their current places of residence. Under the Abbasids, Iranian peoples became better represented in the army and bureaucracy as compared to before. The Abbasid army was centred on the Khurasan Abna al-dawla infantry and the Khurasaniyya heavy cavalry, led by their own semi-autonomous commanders (qa'id) who recruited and deployed their own men with Abbasid resource grants. al-Mu'tasim began the practice of recruiting Turkic slave soldiers from the Samanids into a private army, which allowed him to take over the reins of the caliphate. He abolished the old jund system created by Umar and diverted the salaries of the original Arab military descendants to the Turkic slave soldiers. The Turkic soldiers transformed the style of warfare, as they were known as capable horse archers, trained from childhood to ride. This military was now drafted from the ethnic groups of the faraway borderlands, and were completely separate from the rest of society. Some could not speak Arabic properly. This led to the decline of the caliphate starting with the Anarchy at Samarra.

Civil administration

As a result of such a vast Empire, the caliphate was decentralized and divided into 24 provinces.

Harun's vizier enjoyed close to unchecked powers. Under Harun, a special "bureau of confiscation" was created. This governmental wing made it possible for the vizier to seize the property and riches of any corrupt governor or civil servant. In addition, it allowed governors to confiscate the estates of lower-ranking officials. Finally, the caliph could impose the same penalty on a vizier who fell from grace. As one later caliph put it: "The vizier is our representative throughout the land and amongst our subjects. Therefore, he who obeys him obeys us; and he who obeys us obeys God, and God shall cause him who obeys Him to enter paradise."

Every regional metropolis had a post office and hundreds of roads were paved in order to link the imperial capital with other cities and towns. The empire employed a system of relays to deliver mail. The central post office in Baghdad even had a map with directions that noted the distances between each town. The roads were provided with roadside inns, hospices, and wells and could reach eastward through Persia and Central Asia, to as far as China. The post office not only enhanced civil services but also served as intelligence for the caliph. Mailmen were employed as spies who kept an eye on local affairs.

Early in the days of the caliphate, the Barmakids took the responsibility of shaping the civil service. The family had roots in a Buddhist monastery in northern Afghanistan. In the early 8th century, the family converted to Islam and began to take on a sizable part of the civil administration for the Abbasids.

Capital poured into the caliphate's treasury from a variety of taxes, including a real estate tax; a levy on cattle, gold and silver, and commercial wares; a special tax on non-Muslims; and customs dues.

Trade

Under Harun al-Rashid, maritime trade through the Persian Gulf thrived, with Arab vessels trading as far south as Madagascar and as far east as China, Korea, and Japan. The growing economy of Baghdad and other cities inevitably led to the demand for luxury items and formed a class of entrepreneurs who organized long-range caravans for the trade and then the distribution of their goods. A whole section in the East Baghdad suq was dedicated to Chinese goods.

Much of this direct maritime trade was oriented toward Iraqi markets, particularly Basra and Baghdad, which functioned as major destinations for goods arriving from Tang China. From the seventh to the tenth centuries, merchants from the Gulf served Iraqi markets through direct sea routes linking the Persian Gulf to the South China coast, especially Guangzhou, as attested by both contemporary textual sources and archaeological evidence. The ninth-century Belitung shipwreck, carrying a large cargo of Chinese ceramics, illustrates the scale of this trade and its connection to demand in Iraq and the wider Abbasid realm.

Arabs traded with the Baltic region and made it as far north as the British Isles. Tens of thousands of Arab coins have been discovered in parts of Russia and Sweden, which bear witness to the comprehensive trade networks set up by the Abbasids. King Offa of Mercia (in England) minted gold coins similar to those of the Abbasids in the eighth century.

Muslim merchants employed ports in Bandar Siraf, Basra, and Aden and some Red Sea ports to travel and trade with India and South East Asia. Land routes were also utilized through Central Asia. Arab businessmen were present in China as early as the eighth century. Arab merchants sailed the Caspian Sea to reach and trade with Bukhara and Samarkand.

During the ninth and tenth centuries, large quantities of opaque glazed pottery were produced in southern Iraq, within the heartlands of the Abbasid Caliphate, and exported as a mass-produced commercial commodity.

Finds of this Iraqi ware at sites across the Middle East, South Africa, and Southeast Asia demonstrate sustained commercial interaction between Iraq and the wider Indian Ocean world.