Brian Boru was a powerful Irish monarch who reigned as High King of Ireland from 1002 until his death in 1014. Born around 941 in Killaloe, he rose from being the King of Munster to unify much of the island, effectively challenging the long-standing rule of the Uí Néill. He is credited with significantly curbing Viking influence in Ireland. As the progenitor of the O'Brien dynasty, he remains one of the most significant figures in medieval Irish history.