Europe (pronunciation: / ˈ jʊər ə p / yewr-əp or / ˈ j ɜr ə p / yur-əp) is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting the Black and Aegean Seas. Europe is bordered by the Arctic Ocean and other bodies of water to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and the Black Sea and connected waterways to the southeast. Yet the borders of Europe—a concept dating back to classical antiquity—are somewhat arbitrary, as the primarily physiographic term "continent" can incorporate cultural and political elements.