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–India relations million in 2015-16. Imports from Chad were a mere $150,000 in 2011-12, grew sharply to $157.15 million the following fiscal, before declining by 73% and 52% in the following two fiscal years respectively. Bilateral figures do not reflect the full extent of Chad's imports from India, as the country procures several Indian goods from Dubai, Cameroon and Nigeria. In the 2015-16 financial year, India began importing crude oil from Chad resulting in a 411% increase in imports. Chad's exports to India grew from $62.77 million in 2010-11 to $320.87 million in 2015-16. Crude oil accounted for 97% of the country's