It derived from a branch of the ruling Uí Chóelbad dynasty of Dál nAraidi Magh Line that had conquered the petty kingdom of Eilne at some point in the 7th century.
[1] This branch of the Uí Chóelbad descended from Fiachra Cáech (d. 608), brother of Fiachnae Lurgan, king of Dál nAraidi and over-king of Ulaid.
[2] Cathussach mac Ailello, king of Eilne and Dál nAraidi, and claimed as having ruled the over-kingdom of Ulaid for sixteen years, was killed at Ráith Beithech (Rathveagh, County Antrim) in 749.
[2] The church (or monastery) of Cuil Raithin on the shore of the River Bann lay in Eilne and was said to have been founded by Cairbre, who subsequently became its bishop.
[8] The Airgíallan dynasty of Uí Tuirtrí that lay west of the River Bann had been active east of it from as early as 776,[2] and by the 10th century had taken control of Eilne.