A region on the frontier of Finland and Russia, which formed an independent Finnish state in medieval times and whose folk-tales were the source of the Finnish epic, the Kalevala. In the 16th century Karelia came under Swedish rule and in 1721 it was annexed by Russia. Following Finland’s declaration of independence in 1917, part of Karelia became a region of Finland and part was subsequently designated an autonomous republic of the Soviet Union. After the Russian–Finnish War of 1939–40 the greater part of Finnish Karelia was ceded to the Soviet Union.