Also spelled Yenisei or Enisei, Evenk Ioanesi ("Great River"), River, central Russia is one of the longest rivers in Asia, it rises in the borderland of south-central Russia and Mongolia and flows generally north along the edge of the West Siberian Plain to empty into the Kara Sea. Along its course it receives numerous tributaries, including the Angara River. Approximately 1,900 mi (3,000 km) of the river's 2,540-mi (4,090-km) course (calculated from the Great Yenisey River) are navigable.