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–Nigeria relations on control of desertification, promotion of conservation, rational utilization and development of lands, water resources, flora and fauna. "The Maiduguri Agreement", signed on 18 July 1990, and amended 5 October 1998, further deals with development, conservation, and utilization of the water resources of trans–boundary catchments. The Maiduguri Agreement and Abuja Agreement are overseen by the NNJC. Niger–Nigeria relations The Niger–Nigeria relations refers to the current and historical relationship between Niger and Nigeria. Relations are based on a long shared border and common cultural and historical interactions. The 1,500 kilometer (930 mi) long border between Niger to the north and Nigeria