The Hiberno-Scottish mission was a mission led by Irish and Scottish monks which spread Christianity and established monasteries in Great Britain and continental Europe during the Middle Ages. The mission originated in 563 with the foundation of Iona by the Irish monk Saint Columba, and was initially concerned with ministering to the Gaels of Dál Riata and converting the Picts. Over the next centuries the mission grew in power and influence and spread through Anglo-Saxon England and the Frankish Empire. The early mission is often associated with the Christian practice known as Celtic Christianity, which was distinguished by its organizations around monasteries rather than dioceses and certain ideosyncratic traditions, but the later mission was more continental in character.