Toward the end of the first millennium A.D., the formation of states began across central Chad in the sahelian zone between the desert and the savanna. For almost the next 1,000 years, these states, their relations with each other, and their effects on the peoples who lived in "stateless" societies along their peripheries dominated Chad's political history. Recent research suggests that indigenous Africans founded most of these states, not migrating Arabic-speaking groups, as was believed previously. Nonetheless, immigrants, Arabic-speaking or otherwise, played a significant role, along with Islam, in the formation and early evolution of these states (see Islam , ch. 2).

Most states began as kingdoms, in which the king was considered divine and endowed with temporal and spiritual powers. All states were militaristic (or they did not survive long), but none was able to expand far into southern Chad, where forests and the tsetse fly complicated the use of cavalry. Control over the trans-Saharan trade routes that passed through the region formed the economic basis of these kingdoms. Although many states rose and fell, the most important and durable of the empires were Kanem-Borno, Bagirmi, and Wadai, according to most written sources (mainly court chronicles and writings of Arab traders and travelers).

Data as of December 1988