Early medieval Ireland is famed for its monasticism, and the century running from 540 to 640 is that of the major monastic founders, while also being marked by individual ascetic enthusiasm. For the most part, however, contemporary documentation comprises laconic notices in the annals, with just a scattering of more informative texts such as the Penitential of Finnian and The Alphabet of Piety. Against this background Columbanus stands out as the one figure for whom we have sufficient sources to enable us to discern his monastic vision and to see something of how he put it into practice. From his pen we have six letters, a series of thirteen sermons preached to his monks, a Regula Monachorum and Regula Coenobialis, a penitential and two poems, while within a generation of his death Jonas produced his Life of Columbanus and his Disciples, which, for all its spin-doctoring, was the work of a well-informed author.

There is, however, a problem about taking Columbanus as representative of the formative period of Irish monasticism. Although born in Leinster and trained in Comgall's monastery of Bangor, Columbanus had left Ireland around 591 to go as a peregrinus to the Continent. Thereafter he was based in Frankia, where his most important foundation was Luxeuil, until 610, when he was expelled. However, he escaped being sent back to Ireland and instead found his way to the Bregenz area and then over the Alps to northern Italy, where he founded a final monastery at Bobbio, and died in 615.