The Picts were a group of Late Iron Age and Early Mediaeval Celtic people living in ancient eastern and northern Scotland. There is an association with the geographical distribution of brochs, Brythonic place name elements, and Pictish stones. Picts are recorded from before the Roman conquest of Britain until the 10th century, when they merged with the Gaels. They lived to the north of the rivers Forth and Clyde, and spoke the extinct Pictish language, thought to have been related to the Brythonic languages spoken by the Britons to the south. They are assumed to have been the descendants of the Caledonii and other tribes named by Roman historians or found on the world map of Ptolemy. Pictland, also known as Pictavia, gradually merged with the Gaelic kingdom of Dál Riata to form the Kingdom of Alba (Scotland). Alba expanded, absorbing the Brythonic kingdom of Strathclyde and Bernician Lothian, and by the 11th century the Pictish identity had been subsumed into the "Scots" amalgamation of peoples.