According to the traditional account, found in genealogical sources, Diarmait mac Cerbaill had three known sons, two of whom were called Colmán.
Colmán Bec was regarded as the ancestor of the much less important dynasty of Clann Cholmáin Bic, later Caille Follamain, through a son Óengus.
[4] A number of difficulties have been noted with the chronology of Colmán Már's death in relation to the floruit of his supposed sons and brothers, with the early appearance of his Latinate name, and with the record of the annals.
[6] The first record of Colmán Bec in the annals is in the 560s, when he is reported to have undertaken an expedition to Iardoman—glossed as "Seil and Islay", but sometimes understood to mean the Inner Hebrides more generally—along with Conall mac Comgaill.
The following year there is a report of Colmán Bec's death, fighting against Áed mac Ainmuirech, at the unlocated Belach Dathí.