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
Rail transport in Chad Imperial expansionist policy known as Mittelafrika. In the 1950s a line through Chad from Port Sudan to Nigeria was proposed but opposed by Chad governmental organisations. In 1958 plans for a line from Cameroon the "Société Civile d'Études du Chemin de Fer Douala-Tchad" (SEDOT) was formed, and continued planning led to start of construction in 1964 - the line was constructed as far as Ngaoundéré in Cameroon (the Trans-Cameroon Railway, completed 1975.). Initial plans were for an extension to Moundou in Chad, but this was not completed. In 1959 a multinational agency, the "Agence Transéquatoriale des Communications" (ATEC) was formed