The Battle of Mynydd Carn took place in 1081, as part of a dynastic struggle for control of the Welsh kingdoms of Gwynedd and Deheubarth. The result of the battle had a radical effect on the history of Wales. The battle is recorded in the near-contemporary biography of one of the participants, The History of Gruffydd ap Cynan. Gruffydd ap Cynan was a descendant of the traditional ruling house of Gwynedd, and had previously made an attempt to claim the kingdom in 1075, but had been defeated by Trahaearn ap Caradog and forced to take refuge in Ireland.