Domnall was the second son of Ruaidrí na Saide Buide to assume the kingship. He deposed Domnall mac Tigernáin Ua Ruairc, been assisted by aid of Muirchertach Ua Briain, who was his father Ruaidrí's brother-in-law. Domnall was the last Ua Ruairc of Breifne to become king of Connacht.
