Europe —a concept dating back to classical antiquity— is a continent that comprises the westernmost part of Eurasia. Europe is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, and the Mediterranean Sea to the south. The eastern boundary with Asia is an arbitrary historical and social construct, as there is no clear physical and geographical separation between them. The primarily physiographic term “continent” as applied to Europe also incorporates cultural and political elements whose discontinuities and lines of demarcation are not reflected by the continent’s current overland boundaries with Asia. Europe is considered by historical convention as separated from Asia by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways of the Turkish Straits.