sentences:  In 563, Columba left Ireland and settled with the Gaels of Dál Riata, founding an abbey on Iona, which became one of the oldest Christian religious centers in Western Europe.His reputation as a holy man led to his role as a diplomat among the tribes.He is said by Bede and Adamnán to have ministered to the Gaels of Dál Riata and converted the northern Pictish kingdoms.