Whether or not Cairpre was in fact a son of Niall Noígiallach (qv) and Rígnach, daughter of Meda, he is represented as such by Tírechán (qv) in his late seventh-century ‘Collectanea’ (§9). This claim of paternity may be questioned on the grounds that Niall is credited with fourteen sons, all ancestral figures of ruling lineages, whose respective chronologies pose seemingly irreconcilable difficulties. Cairpre features in the ‘Vita Prima’ (7th/8th cent.) of St Brigit (qv) as a brother and rival of Conall Cremthainne (qv) son of Niall, and his position in the Uí Néill schema was firm by the time the genealogies were compiled, but ‘Baile Chuinn’ is silent about his parentage. Historically, Cairpre was perhaps a representative of an early midland dynasty, which had become affiliated to the Uí Néill by (perhaps) the later sixth century, but was later marginalised by Conall's descendants. The non-contemporary annals that chart the fifth- to sixth-century warfare between the Uí Néill and the Leinstermen name Cairpre as the victor in battles fought at Granard, Teltown, Lough Slevin, and Cenn Ailbe, assigned to the years 485, 494, 499, and 501. This could be interpreted either as a recollection of campaigns fought by Cairpre in person, or by the dynasty that claimed descent from him.
It seems clear that Cenél Cairpri had already ceased to be of prime political importance by the second half of the seventh century; presumably this is the significance of the episode in Tírechán's ‘Collectanea’ in which Cairpre is cursed for his defiant paganism and told that his line will produce no future kings. The marginalisation of Cenél Cairpri in the historical period is further illustrated by the so-called ‘Timna Néill’ (the testimony of Niall), in which the patriarch grants the borders of his realm to Cairpre.