Erc was king of Irish Dál Riata until 474. He was the father of three sons: Fergus Mór, Loarn and Oengus. He also may have been the great-grandfather of Muirchertach mac Muiredaig. Confusion arises from the latter's matronym, Macc Ercae, said to come from his legendary mother Erca, daughter of Loarn mac Eirc. She married Muiredach mac Eógain. According to the Duan Albanach and the Senchus Fer n-Alban, Erc of Dál Riata's father was Eochaid Muinremuir, son of Áengus Fert, son of Fedlimid, son of Oengus, son of another Fedlimid, son of Senchormaich, son of Cruitlinde, son of Findfece, son of Archircir, son of Eochaid Antoit, son of Fiacha Cathmail, son of Cairbre Riata, son of Conaire Cóem and Saraid ingen Chuinn.