He was once held to be the author of the Annals of Tigernach, hence its name; this view is no longer sustainable, though the nature and extent of his involvement remain unclear.
The annalistic compilation known as the Chronicon Scotorum mentions that he was 'heir of Ciarán and of Commán', that is abbot of Clonmacnoise and Roscommon, and came from the Síol Muireadaigh (Síl Muiredaig),[1] descendants of Muiredach Muillethan (d. 702), a ruling sept of the Connachta Uí Briúin dynasty.
[2] The Uí Braín were a branch of the Síl Muiredaig, but being no player in the race for kingship, focused on Clonmacnoise to pursue a career in the church instead.
[2] The Annals of Ulster and the Chronicon Scotorum record Tigernach's death under the entry for 1088.
[1][2][3] The copy of the Annals of Tigernach which is preserved in the 14th-century manuscript Oxford, Bodleian Library, MS Rawlinson B.