O'Donnell dynasty

The O'Donnell dynasty (Irish:Ó Dónaill or Ó Domhnaill; derived from the Irish name Domhnall, which means "ruler of the world", Dónall in modern Irish) were an ancient and powerful Irish family, kings, princes and lords of Tyrconnell (Tír Chonaill in Irish, now County Donegal) in early times, and the chief allies and sometimes rivals of the O'Neills in Ulster.