The earliest known inhabitants of Chad were the Sao people, who built walled cities in the area southeast of Lake Chad in about 500 B.C. Beginning in 800 A.D., people from north Africa migrated into the area.

The Kanem empire was established in the northern part of present-day Chad by a federation of nomadic peoples in about 1000 A.D. Its ruler was known as the Mai and was considered divine. During the 10th century, the Islamic religion spread throughout the empire. In the 13th century, the kingdom established a capital at Njimi, northeast of Lake Chad. The capital was moved to Bornu, on the western edge of Lake Chad, at the end of the 14th century. The Kanem-Bornu empire, as it became known, reached the height of its power and influence during the reign of Mai Idris Aluma, at the end of the 16th century.

The principality of Baguirmi was formed in an area to the southwest of the Kanem-Bornu empire in the 16th century. It became powerful in the 17th century and tried unsuccessfully to expand into the territory of Kanem-Bornu. At the same time, northeast of Baguirmi, an Arabic-speaking sultanate, Ouaddaï, was established. In the early 19th century it began to expand under the leadership of Sultan Mohammed Sharif, taking over Baguirmi and attacking Kanem-Bornu.

When the European colonial powers sought to colonize Africa in the 19th century, Chad was one of the last regions to be conquered. The French invaded from Congo, to the south, where they were well established. They encountered an army led by Rabah Fadlallah, a former slave who had become a powerful military leader and had subjugated Baguirmi and Kanem-Bornu. In 1900, Rabah's forces were defeated by a Franco-Baguirmi alliance in the battle of Kousseri (in present-day Cameroon).

   Did you know?
Chad australopithecine is a type of early hominid identified from the remains of a single body found in 1960 at Koro Toro in southeast Chad. The remains were found close by the teeth of an extinct elephant and are thought to be 200,000 to 500,000 years old.
During the early 20th century, the French colonized the south of Chad and, in 1920, sent the French Foreign Legion to conquer the northern territories. They forced the inhabitants to grow cotton. Because most of the arable land was used to grow cotton, the people suffered food shortages. Many people died from famines and the harsh conditions of forced labour.

Forced labour was abolished in 1946 and Chadians were declared French citizens. Chadians elected a Territorial Assembly and sent delegates to the French National Assembly. Universal suffrage was introduced in 1956. In 1960, Chad became an independent country, but Francois Tombalbaye, Chad's first leader after independence, was unable to unite the country's various groups. In 1975 he was killed in a military coup d'état. For many years, the country was torn by a civil war in which many thousands of Chadians died, until a military leader called Idriss Déby seized power in 1990. In 1996, Déby won a widely contested presidential election and became constitutional president of Chad.