 Complete the following phrase:  Beginning in the 7th millennium BC, human populations moved into the Chadian basin in great numbers. By the end of the 1st millennium AD, a series of states and empires had risen and fallen in Chads Sahelian strip, each focused on controlling the trans-Saharan trade routes that passed through the region. France conquered the territory by 1920 and incorporated it as part of French Equatorial Africa. In 1960, Chad obtained independence under the leadership of François Tombalbaye. Resentment towards his policies in the Muslim north culminated in the eruption of a long-lasting 