[1] The pagan Celts of Britain had already been extensively Christianized during the Roman period: although only four victims of Diocletian's persecution are now known (Saints Alban, "Amphibalus", and Julius and Aaron),[2] Britons met the pagan Saxon invaders largely as Christians prior to being driven back to Wales, Cornwall, and Brittany.
Although they largely refrained from missionizing among the Germans, Welsh refugees and missionaries were responsible for the Christianization of Ireland[3] and Brittany.
Extreme cases are Irish accounts of Gerald of Mayo's presiding over 3300 "saints" and Welsh claims that Bardsey held the remains of 20 000.
Such communities were organized on tribal models: founding saints were almost invariably lesser members of local dynasties and their successors chosen from among their kin.
[7] By some estimates,[8] these traditions produced over 800 pre-congregational saints venerated locally in Wales, but invasions by Saxons, Irishmen, Vikings, Normans, and others destroyed many ecclesiastical records.