Excerpts from Books and Wikipedia
"Chad, straddling the African Transition Zone as well as the regional boundary with West Africa, is one of the realm’s most remote countries; poverty is rife, although recent oil discoveries in the south and assistance from China in exploiting those reserves are today slowly changing its status." [Geography: Realms, Regions, and Concepts, 17th Edition, p. 314]
"Chad’s difficulties began soon after independence when its first president, François Tombalbaye, a southerner from the Sara tribe, imposed an increasingly repressive regime from Fort Lamy, dealing particularly harshly with the Muslim population whom he disliked and distrusted." [The Fate of Africa, p. 347]