In 563 AD Columba left Ireland and settled with the Gaels of Dál Riata, where he was granted the Island of Iona to found his monastery.
The traditional opinion of how Columba came to Scotland states that after being ordained as into the priesthood in Ireland, Columba became involved in a violent quarrel with a colleague. The quarrel led to bloodshed and Columba was exiled from Ireland. In the Gaelic kingdom of Dál Riata he found a warm welcome.
For the Gaelic warrior kings, Columba was a useful asset. His monastery provided education for their sons, he was a close advisor to the king, and he served as a diplomat to the king's neighbours in Pictland and Ireland. Columba's blessing was treasured by kings - a powerful symbol of their authority, and, in return for Columba's support, the Gaels gave the monastery land and protection.
Columba died in 597, but his monastery's influence continued to grow, leading to the foundation of new monasteries in Ireland and as far away as Lindisfarne in Northumbria. In Pictland, Columban monks began to spread the word of Christianity in the seventh century.
Iona faced competition from other Irish monastic missions, however, and their religious power was not absolute. St Mael Rhuba at Applecross or St Donnan, who was martyred on the Isle of Eigg, were also contenders as early spiritual leaders of the Church.
Columba himself would have remained an enigmatic and little-known figure were it not for Adomnán, the ninth Abbot of Iona, and his book, the Vita Colum Cille (Life of Columba), which ensured that the saint's reputation eclipsed that of the other Scottish saints and spread Iona's fame across Christendom.
According to Adomnán's account Columba tried to spread the Christian Gospel to pagan people of Pictland. Columba is reported as travelling to the north of the country to meet a Pictish king and engaging a battle of wills and theology with a Pictish druid. Despite such encounters, Pictland would remain pagan for a while longer.
Pilgrimage to Iona increased: kings wished to be buried near to Columba, and a network of Celtic high crosses and processional routes developed around his shrine. At its zenith Iona produced The Book of Kells, a masterpiece of Dark Age European art.
Shortly after however, in 794 AD, the Vikings descended on Iona, and, within 50 years, they had extinguished the light which had been Iona. Columba's relics were finally removed in 849 AD and divided between Alba and Ireland.
The Monymusk Reliquary, from around 750 AD, probably contained a relic of St Columba. It became a powerful symbol of nationhood, and was carried before the Scots army as it marched into war.
This reliquary is thought to be the Brechbennoch which was carried by the Scots at the Battle of Bannockburn in 1314.