Native Briton kingdom that, from about the 6th century, had extended over the basin of the River Clyde and adjacent western coastal districts, the former county of Ayr. Its capital was Dumbarton, then known as Alclut. Its people were in frequent conflict with the Anglo-Saxons of Northumbria and later the Scots of Dálriada. They were converted to Christianity by St. Ninian and his successors from the monastery of Whithorn. It became a province of Scotland in 1016/1018.