The Siverskyi Donets or Seversky Donets , usually simply called the Donets, is a river on the south of the East European Plain. It is the fourth longest river in Ukraine. Donets originates in the Central Russian Upland, north of Belgorod, flows south-east through Ukraine (Kharkiv, Donetsk and Luhansk Oblasts) and then again through Russia (Rostov Oblast) to join the Don River, about from the Sea of Azov. The Donets is the fourth largest river in Ukraine and the biggest in the Eastern Ukraine. It is an important source of fresh water in the east of the country. It gives its name to the Donets Basin, known commonly as the Donbass, an important coal mining region in Ukraine.