NO ONE has ever been quite sure where Europe ends and Asia starts. In the Middle Ages geographers drew the border along various rivers, including the Dnieper and the Volga. By the 1950s the Soviet Union settled on a line running down the Ural mountains, and along the ridge of the Caucasus between the Black and Caspian Seas.

NO ONE has ever been quite sure where Europe ends and Asia starts. In the Middle Ages geographers drew the border along various rivers, including the Dnieper and the Volga. By the 1950s the Soviet Union settled on a line running down the Ural mountains, and along the ridge of the Caucasus between the Black and Caspian Seas.