[3] A written account is included in the Brut y Tywysogion, the medieval Welsh chronicle of the princes.
[4] It is also referred to in the work of medieval poets such as Lewys Glyn Cothi.
Gruffydd left two sons— Maredudd and Idwal–who in 1070 challenged Bleddyn and Rhiwallon at Mechain in an attempt to win back part of their father's kingdom.
However, both sons were defeated, Idwal (or Ithel) being killed in combat and Maredudd dying of exposure after the battle.
Rhiwallon was also killed in this battle, leaving Bleddyn to rule Gwynedd and Powys alone.