Western Siberia or West Siberia (Russian: Западная Сибирь, IPA: [ˈzapədnəjə sʲɪˈbʲirʲ]; Kazakh: Batys Sıbır, IPA: [bɑˈtə̥s sɘˈbɘr]) is a region in North Asia. It is part of the wider region of Siberia that is mostly located in the Russian Federation, with a Southern part in Kazakhstan. It lies between the Ural region and the Yenisei River, which conventionally divides Siberia into two halves.
Western Siberia covers an area of 2,500,000 square kilometers (970,000 sq mi), nearly 80% of which is located within the West Siberian Plain. The largest rivers of the region are the Irtysh and the Ob. All major rivers of Western Siberia belong to the Kara Sea basin.