Cynfyn ap Gwerstan.

About Cynfyn ap Gwerstan

Bleddyn ap Cynfyn (Middle Welsh: Bledẏnt uab Kẏnỽẏn;, sometimes spelled Blethyn, was an 11th-century Welsh king. King Harold Godwinson and Tostig Godwinson installed Bleddyn and his brother, Rhiwallon, as the co-rulers of kingdom of Gwynedd on his father's death in 1063, during their destruction of the kingdom of their half-brother, king Gruffydd ap Llywelyn. Bleddyn became king of Powys and co-ruler of the Kingdom of Gwynedd with his brother Rhiwallon from 1063 to 1075. His descendants continued to rule Powys as the House of Mathrafal.