The Seversky Donets or Siverskyi Donets, usually simply called the Donets, is a river on the south of the East European Plain. It originates in the Central Russian Upland, north of Belgorod, flows south-east through Ukraine and then again through Russia to join the river Don, about 100 km (62 mi) from the Sea of Azov. The Donets is the fourth-longest river in Ukraine, and the largest in eastern Ukraine, where it is an important source of fresh water. It gives its name to the Donets Basin, known commonly as the Donbas, an important coal-mining and industrial region in Ukraine.