Chad (Arabic: تشاد; French: Tchad), officially the Republic of Chad, is a landlocked country in Central Africa. It borders Libya to the north, Sudan to the east, the Central African Republic to the south, Cameroon and Nigeria to the southwest, and Niger to the west. Due to its distance from the sea and its largely desert climate, the country is sometimes referred to as the "Dead Heart of Africa".

The territory now known as Chad possesses some of the richest archaeological sites in Africa. A hominid skull was found by Michel Brunet, that is more than 7 million years old, the oldest discovered anywhere in the world; it has been given the name Sahelanthropus tchadensis. In 1996 Brunet unearthed a hominid jaw, which he named Australopithecus bahrelghazali, unofficially dubbed Abel. It was dated using beryllium-based radiometric dating as living c. 3.6 million years ago.

During the 7th millennium BC, the northern half of Chad was part of a broad expanse of land, stretching from the Indus River in the east to the Atlantic Ocean in the west, in which ecological conditions favored early human settlement. Rock art of the "Round Head" style, found in the Ennedi region, has been dated to before the 7th millennium BC and, because of the tools with which the rocks were carved and the scenes they depict, may represent the oldest evidence in the Sahara of Neolithic industries. Many of the pottery-making and Neolithic activities in Ennedi date back further than any of those of the Nile Valley to the east.

In the prehistoric period, Chad was much wetter than it is today, as evidenced by large game animals depicted in rock paintings in the Tibesti and Borkou regions.

Recent linguistic research suggests that all of 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, 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 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.

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–Bornu, Baguirmi, and Ouaddai, according to most written sources (mainly court chronicles and writings of Arab traders and travelers).Chad – Era of Empires, A.D. 900–1900

The Kanem Empire originated in the 9th century AD to the northeast of Lake Chad. Historians agree that the leaders of the new state were ancestors of the Kanembu people. Toward the end of the 11th century the Sayfawa king (or mai, the title of the Sayfawa rulers) Hummay, converted to Islam. In the following century the Sayfawa rulers expanded southward into Kanem, where was to rise their first capital, Njimi. Kanem's expansion peaked during the long and energetic reign of Mai Dunama Dabbalemi (c. 1221–1259).