Wikipedia
Eilne
Eilne, also spelt as Eilni, alias Mag nEilne, was a medieval Irish Cruthin petty-kingdom in the over-kingdom of Ulaid. It lay between the River Bann and River Bush, and was centered on Magh nEilne, the "plain of Eilne", spanning north-east County Londonderry and north-west County Antrim, in present-day Northern Ireland. Eilne may represent the name of an original population grouping, though even in the Old Irish period who they were was forgotten.
The end result of conquest first by the Dál nAraidi and then the Uí Tuirtri resulted in Eilne later becoming known simply as An Tuaiscert, which survived into the late medieval period as the name of a medieval deanery and the Anglo-Norman cantred of Twescard.