Wikipedia
The Cruthin ( Old Irish, ; Middle Irish: or ; Modern Irish: ) were a people of early Ireland, who occupied parts of the present day Counties of Antrim, Laois, Galway, Londonderry and Down in the early medieval period.
The Cruthin comprised a number of túatha, including the Dál nAraidi in southern Antrim and the Uí Echach Cobo in western Down. Early sources preserve a distinction between the Cruthin and the Ulaid, who gave their name to the province of Ulster, although the Dál nAraide claimed in their genealogies to be na fir Ulaid, "the true Ulaid". The Loígis, who gave their name to County Laois in Leinster, and the Sogain of Connacht are also claimed as Cruthin in early Irish genealogies.
By the late 8th century, the Dál nAraidi had secured their over-kingship of the Cruthin and their name replaced that of the Cruthin.