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
Cameroon–Nigeria relations of not doing enough to fight Boko Haram even though the terrorist group frequently crosses into Cameroonian territory. Cameroon has been attacked several times by Boko Haram. Border closures after attacks in Nigeria in 2012 to prevent further infiltration by Boko Haram had a negative impact on the Cameroonian economy. In May 2014, in the wake of the Chibok schoolgirl kidnapping, "[Cameroon's] defense minister Edgard Allain Mebe Ngo'o met with Chad's minister of national defense, Benaindo Tatola, in Yaounde. Ngo'o said Chad had also deployed troops to work together with Cameroonian forces on the borders with Nigeria. He also said