King of Leinster had risen against Brian's claims. The latter were subdued at Glenmama in 999, before rebelling again in 1014 at Clontarf where Norse power in Ireland was finally broken, though Brian died in the process. In the interim, Malachy had passed the High Kingship to Brian in 1002 and he built strong Christian links to Armagh. After the death of Brian, his two established surviving sons; Donagh and Teague; struggled in an internal Dál gCais rivalry for dominion. While Donagh was High King, many other Irish kings allied against him, including Leinster, Connacht, and Ulster. Deposed in 1063, he fled to Rome, with some sources claiming he granted Pope Urban II the Irish crown, this is controversial, however. Teague's son Turlough took up the reins in a lasting alliance with the powerful Dermot Kinsella, King of Leinster. Not a military leader, Turlough was instead a capable politician, the Cogad Gáedel re Gallaib glorifying Brian's feats would be authored during his lifetime. Turlough's son Murtagh would be the last High King from the Dál gCais of the medieval period, reigning between 1101–19. Murtagh attempted to make the Irish kingship more along the lines of European monarchies and was involved in foreign affairs (allying with Arnulf de Montgomery in the Welsh Marches against Henry I, King of England), trying to extend Irish influence beyond internal rivalries. Dynastic divisions Septs and kindreds The septs of the Dál gCais developed over time, with new ones breaking off to form separate surnames at different times, but all claiming to share the same paternal line (with a few biological exceptions along the way due to adoption or extra-marital issue). Their eponymous founder Cas had several sons; two of them gave their names to the Uí Bloid and Uí Caisin kindreds, another founded the Ui Fearmaic. As the proto-Dál gCais moved up into what is today East Clare, these became associated with rooted tribal areas, but were themselves internally divided into any other septs. The senior line descended from Cas' first son Bloid and they provided the Kings of Thomond. Initially the leaders of the tribe were a sept known as the Uí Aengusa from which descends O'Curry, O'Cormacan and O'Seasnain. However, during the 10th century, this passed to the junior Uí Thairdelbaig. It is this kindred which would furnish the High Kings of Ireland and the Kings of Thomond including Brian Bóruma. From the