The Story of Ancient Irish Civilization — P.W. Joyce

" ...]of these migrations of which we have reliable accounts originated in a famine, exactly as the great exodus of our own day from Ireland to America was set going by the terrible famine of 1847. And this migration is related partly by old Irish writers, and partly by the great English historian, the Venerable Bede. The famine in question fell on Munster early in the third century, so that numbers of people were forced to leave the province. One particular chief led a ...]."