The continent of Asia is defined by subtracting
Europe and Africa from the great land mass of Africa-Eurasia. The
boundaries are vague, especially between Asia and Europe: Asia and
Africa meet somewhere near the Suez Canal. The boundary between
Asia and Europe runs via the Dardanelles, the Sea of Marmara, the
Bosphorus, the Black Sea, the ridges of the Caucasus (according to
others, through the Kuma-Manych Depression), the Caspian Sea, the
Ural River (according to others, the Emba River) and the Ural
Mountains to Novaya Zemlya. About 60% of the world's population
live in Asia.
