- Back to Medieval Source Book Medieval Sourcebook: Rule of St. Columba 6th Century Even if it did not quite save civilization , Ireland was one of the monastic centers of Europe in the early middle ages. In fact the Church in Ireland was dominated by monasteries and by monastic leaders. Other Irish monks became missionaries and converted much of Northern Europe St. Columba (521 -597) and his ...www.fordham.edu/halsall/source/columba-rule.html