Central Africa is a core region of the African continent often considered to include Burundi, the Central African Republic, Chad, Democratic Republic of the Congo, and Rwanda. Central Africa, sometimes referred to as Middle Africa, defines a portion of the African continent south of the Sahara Desert, east of Western Africa, and west of the Great Rift Valley. According to the UN, the nine countries of Middle Africa are Angola, Cameroon, Central African Republic, Chad, Democratic Republic of the Congo, Republic of the Congo, Equatorial Guinea, Gabon, and Sao Tome and Principe. All of the states in the UN sub region of Middle Africa, plus those otherwise commonly reckoned in central Africa (11 states in total), comprise the Economic (ECCAS). Middle Africa is one of the most resource-rich regions on the African continent. Both Chad and Equatorial Guinea have oil resources to develop. The two biggest economies are Cameroon (which produces thirty percent of Middle Africas total GNP) and Zaire (which despite its state still produces twenty percent of the areas GNP).