Asia, largest of the earth's seven continents. With outlying islands, it covers an estimated 44,936,000 sq km (17,350,000 sq mi), or about one-third of the world's total land area. Asia has more than 3.2 billion inhabitants. Its peoples account for three-fifths of the world's population. Lying almost entirely in the northern hemisphere, Asia is bounded by the Arctic, Pacific, and Indian oceans. The conventional boundary between Europe and Asia is drawn at the Ural Mountains in Russia. Asia and Africa are separated by the Red Sea. Asia is divided for convenience into five major realms: the areas of the former Union of Soviet Socialist Repu