Note: General area in north central Africa, south of the Sahara and Libyan deserts, including Senegal basin, central parts of Niger and Nile basins. The area had settlements 30,000 BCE; home to Nilo-Saharan and Niger-Kodofanian civilizations; occupied by Libya then Egypt 2000 BCE; Christian and Muslim states were established; medieval home of great Negro Empires of Bornu, Songhai, and Fulah. Area was conquered by Egypt 1820; ravaged by slave trade in the 19th century; joint British/Egyptian rule began in early 20th century. South Sudan separated from the nation of Sudan in 2011.