 The modern border follows the Aegean Sea, the Dardanelles–Sea of Marmara–Bosphorus (together known as the Turkish Straits), the Black Sea, along the watershed of the Greater Caucasus, the northwestern portion of the Caspian Sea and along the Ural River and Ural Mountains to the Kara Sea, as mapped and listed in most atlases including that of the National Geographic Society and as described in the World Factbook.According to this definition, Georgia and Azerbaijan both have most of their territory in Asia, although each has small parts of their northern borderlands north of the Greater Caucasus watershed and thus in Europe.Though most geographic sources assign the area south of the Caucasus Mountain crest to Southwest or West Asia, no definition is entirely satisfactory, with it often becoming a matter of self-identification.