The Viking Age brought great changes in Britain and Ireland, no less in Scotland than elsewhere, with the Vikings conquering and settling the islands and various mainland areas, including Caithness, Sutherland and Galloway. In the middle of the 9th century Ketil Flatnose is said to have founded the Kingdom of the Isles, governing many of these territories, and by the end of that century the Vikings had destroyed the Kingdom of Northumbria, greatly weakened the Kingdom of Strathclyde, and founded the Kingdom of York. In a major battle in 839, the Vikings killed the King of Fortriu, Eógan mac Óengusa, the King of Dál Riata Áed mac Boanta, and many others. In the aftermath, in the 840s, Cínaed mac Ailpín (Kenneth MacAlpin) became king of the Picts.