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 transnational grassroots environmental network. The organization brings together and mobilizes social and environmental advocacy groups from all over the world to rally behind certain issues. While FOE has been involved in documentation and monitoring of pipeline project since its construction, the organization more recently developed a report in 2008 condemning a World Bank initiative for "New Climate Funds". Along with four other advocacy organizations, FOE stated that the World Bank had repeatedly engaged in projects, such as the Chad-Cameroon pipeline, that actually negatively affected the environment and only added to pollution. The Center for Environment and Development is a Cameroon-based