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
Niger River Fund. The World Bank approved a US$500 million soft loan in July 2007 to finance projects in the basin over a 12-year period. Funding will be awarded in two phases. The initial $185 million credit will go to Nigeria, Guinea, Benin, Mali and Niger. The second, $315 million investment, is slated for Burkina Faso, Cameroon, Chad and Ivory Coast. Besides financing the rehabilitation of dams in Nigeria, the loan will also fund the "sustainable management of selected degraded ecosystems and rehabilitation of small water infrastructure" and capacity building. In September 2009, the Nigerian government commenced a 36 billion naira dredging