[3] He was the son of Rónán mac Tinne by Ronat, a woman from another Northern Uí Néill lineage known as the Cenél nÉnda.

Some of Adomnán's childhood anecdotes seem to confirm at least an upbringing in this fertile eastern part of present-day County Donegal, not far from the modern city of Derry.

It has been suggested by Alfred Smyth that Adomnán spent some years teaching and studying at Durrow,[4] and while this is not accepted by all scholars, it remains a strong possibility.

It is sometimes thought, after the account given by Bede, that it was during his visits to Northumbria, under the influence of Abbot Ceolfrith, that Adomnán decided to adopt the Roman dating of Easter that had been agreed some years before at the Synod of Whitby.

Jeffrey Wetherill sees Adomnán's long absences from Iona as having led to something of an undermining of his authority; he was thus unable to persuade the monks to adopt the Roman dating of Easter, let alone the tonsure.

When Adomnán learned of this he left Iona to see the king and scolded him soundly for yielding the rights of the Uí Néill.

The Cáin Adomnáin was promulgated amongst a gathering of Irish, Dál Riatan and Pictish notables at the Synod of Birr in 697.

[11] Wetherill suggests that one of the motivations for writing the Vita was to offer Columba as a model for the monks, and thereby improve Adomnán's standing as abbot.

[4] Also attributed to him is a good deal of Gaelic poetry, including a celebration of the Pictish King Bridei's (671–93) victory over the Northumbrians at the Battle of Dun Nechtain (685).

Along with Columba, he is joint patron of the Roman Catholic Diocese of Raphoe, which encompasses the bulk of County Donegal in the north-west of Ireland.