The modern border between Asia and Europe remains a historical and cultural construct, defined only by convention. 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.