History of Chad Africa's major language groupings south of the Sahara Desert (except Khoisan, which is not considered a valid genetic grouping anyway), i. e. the Afro-Asiatic, Nilo-Saharan and Niger–Congo phyla, originated in prehistoric times in a narrow band between Lake Chad and the Nile Valley. The origins of Chad's peoples, however, remain unclear. Several of the proven archaeological sites have been only partially studied, and other sites of great potential have yet to be mapped. At the end of the 1st millennium AD, the formation of states began across central Chad in the sahelian zone between the desert and the savanna. For
Geography of Chad extends west into Nigeria and Niger. The larger, northern portion of the basin is bounded within Chad by the Tibesti Mountains in the northwest, the Ennedi Plateau in the northeast, the Ouaddaï Highlands in the east along the border with Sudan, the Guéra Massif in central Chad, and the Mandara Mountains along Chad's southwestern border with Cameroon. The smaller, southern part of the basin falls almost exclusively in Chad. It is delimited in the north by the Guéra Massif, in the south by highlands 250 kilometers south of the border with Central African Republic, and in the southwest by the