Before its creation, the barony of Coleraine was a region known as Firnacreeve, or simply "the Creeve", a territory ruled at an early date by the Airgiallan people of Fir na Craoibhe (English: men of the tree/branch).

[6] At some point another Airgillian people known as the Fir Li (claimed to be descended from Colla Uais) came to dominance in the region between the River Moyola and the Camus (south of Coleraine), covering over half the territory of Firnacreeve.

[6] The Fir Li would eventually fall under the domination of the Cenél nEóghain by the 9th century, with many being driven east across the River Bann.

[7] Along with the territory of Tirkeeran; Keenaght and Firnacreeve would form the basis of Tircahan or Cathanaght both signifying "O'Cahans Country"[8] and later County Coleraine.

In the Annals, Fir na Craoibhe is noted by various names such as; Craebh, Craoibhe, Craibh, Firna-craibhe, and so on:[6] When the baronies of Ulster were being created by the English around 1585, the general manner was to name it after the principal town or castle lying within the area, in which they held their court, baron, and gaol.