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
Chad–Cameroon Petroleum Development and Pipeline Project immunity and detained for nine months. In November 2000, the World Bank announced that $4 million of a $25 million signing bonus from the oil companies was spent by the Chadian government on weapons. The World Bank required tight restrictions on oil revenues as a condition of its loans. In January 2006, Chad moved to unilaterally increase the portion of oil revenues going to its general fund from 15 to 30 percent. On 28 August 2006, President Déby ordered Chevron and Petronas to quit the country. In Chad and especially Cameroon, through which the pipeline stretches 890 km of the