The traditional story is that he was born in Cumbria but travelled to Rome as a young man to study Christianity. There he was made a bishop and given the task of converting the Picts by the Pope, St Siricus.
Tradition (first mentioned by Bede) states that around 397 he set up his base at Whithorn in Southwest Scotland, building a stone church there, known as the Candida Casa which means the White House. From there he began work among the Britons of the surrounding area. Later he undertook a journey northwards along the east coast in order to spread Christianity among the southern Picts. The word southern is almost certainly a misnomer based on the maps of early times which mistakenly depict the east coast of Scotland as if it were the south coast. Placename evidence and local tradition suggest that he may have travelled as far as the Shetland Islands. He trained many missionaries, among whom, it is said, was the man who converted Saint Columba.