Истрад-Тиви
In 1073, Robert of Rhuddlan stealthily established his forces on the banks of the River Clwyd and attempted to ambush and capture Bleddyn. He narrowly failed, but seized valuable booty in raids further south. Bleddyn was killed in 1075 by King Rhys ab Owain of Deheubarth, having been betrayed by the lords of Ystrad Tywi. When Rhys was later defeated at the 1078 Battle of Goodwick by Bleddyn's successor, Trahaearn ap Caradog, and killed by Caradog ap Gruffydd of Gwent shortly afterwards, this was hailed as "vengeance for the blood of Bleddyn ap Cynfyn". After his death, Gwynedd was seized by Trahaearn and later recovered for the House of Aberffraw by Gruffudd ap Cynan; but in Powys, Bleddyn was the founder of a dynasty which lasted until the end of the 13th century.