As a youth, he was one of the fifty hostages whom the princes of Ireland gave to king Lóegaire mac Néill, by whom he was set free at the intercession of Bishop Ciarán.
[1] Returning to his native country, he converted great numbers to Christianity in Connacht.
According to manuscripts extant in the library at Cambridge, Cianán built here a church of stone, on that account called Damliag, corrupted into Duleek.
It also could explain the confusion over the site of his stone church being located in accounts within the territory of Eoghan, in north Ulster, while actually at Duleek in County Meath.
Duleek having suffered greatly by several fires and devastations of the Danes, its episcopal see was united to the diocese of Meath.