Menteith and who raided along the eastern coast into modern England. Christian missionaries from Iona appear to have begun the conversion of the Picts to Christianity from 563. In the west were the Gaelic (Goidelic)-speaking people of Dál Riata with their royal fortress at Dunadd in Argyll, with close links with the island of Ireland, from which they brought with them the name Scots. In 563 a mission from Ireland under St. Columba founded the monastery of Iona off the west coast of Scotland and probably began the conversion of the region to Christianity. The kingdom reached its height under Áedán mac Gabráin (r. 574–608), but its expansion was checked at the Battle of Degsastan in 603 by Æthelfrith of Northumbria. In the south was the British (Brythonic) Kingdom of Strathclyde, descendants of the peoples of the Roman influenced kingdoms of "The Old North", often named Alt Clut, the Brythonic name for their capital at Dumbarton Rock. In 642, they defeated the men of Dál Riata, but the kingdom suffered a number of attacks from the Picts, and later their Northumbrian allies, between 744 and 756. After this, little is recorded until Alt Clut was burnt and probably destroyed in 780, although by whom and what in what circumstances is not known. Finally, there were the English or "Angles", Germanic invaders who had conquered much of southern Britain and held the Kingdom of Bernicia, in the south-east. The first English king in the historical record is Ida, who is said to have obtained the throne and the kingdom about 547. Ida's grandson, Æthelfrith, united his kingdom with Deira to the south to form Northumbria around the year 604. There were changes of dynasty, and the kingdom was divided, but it was re-united under Æthelfrith's son Oswald (r. 634–42), who had converted to Christianity while in exile in Dál Riata and looked to Iona for missionaries to help convert his kingdom. Origins of the Kingdom of Alba This situation was transformed in AD 793 when ferocious Viking raids began on monasteries like Iona and Lindisfarne, creating fear and confusion across the kingdoms of North Britain. Orkney, Shetland and the Western Isles eventually fell to the Norsemen. The King of Fortriu, Eógan mac Óengusa, and the King of Dál Riata Áed mac Boanta, were among the dead in a major defeat at the hands of the Vikings in 839. A mixture of