Under the commonly used geographic definition, the boundary between the continents of Asia and Europe stretches along the Ural Mountains,the Ural River, and the Caspian Sea in the east, the Greater Caucasus range, and the Black Sea with its outlets, the Bosphorus and the Dardanelles, in the south. Based on such a commonly used division of the continents, the transcontinental states of Azerbaijan, Georgia, Kazakhstan, Russia, and Turkey have territory in both Europe and Asia. While four of those transcontinental countries are generally associated with Asia, Russia, even though it is partly in Europe, is considered to be a European country because of its historical, cultural, political, and ethnic ties to the continent.