Medieval Celtic kingdom, Scotland. Located south of the River Clyde, it was established in the 6th century. Its capital was Dumbarton. The Picts and Vikings ravaged the kingdom in the 8th–9th centuries. It suffered several defeats by the English, who took it over in the early 10th century. The Anglo-Saxon King Edmund I leased it in 945 to the Scots king Malcolm I. It became a province of Scotland in the 11th century after the death of its king, who had helped Malcolm II defeat the English at Carham.