The Pontic-Caspian steppe begins near the mouth of the Danube and extends northeast almost to Kazan and then southeast to the southern tip of the Ural Mountains. Its northern edge was a broad band of forest steppe which has now been obliterated by the conversion of the whole area to agricultural land. In the southeast the Black Sea-Caspian Steppe extends between the Black Sea and Caspian Sea to the Caucasus Mountains. In the west, the Great Hungarian Plain is an island of steppe separated from the main steppe by the mountains of Transylvania. On the north shore of the Black Sea, the Crimean Peninsula has some interior steppe and ports on the south coast which link the steppe to the civilizations of the Mediterranean basin.