Among Rwanda's earliest known inhabitants were the Hutu, who migrated into the area from the west. After the arrival of the Tutsi from the north about the 16th century, the Hutu were forced into servitude in a Tutsi-dominated feudal state. Rwanda became part of German East Africa in 1899, and after World War I was made part of the League of Nations mandate of Ruanda-Urundi (which later became a United Nations trust territory) under Belgian administration.

The Tutsi continued their rule over the Hutu until 1959, when the Hutu revolted and drove thousands of Tutsi from Rwanda. In 1961 the mwami (the Tutsi king) was deposed and the people voted to establish a republic, with the Hutu winning control of the government. Rwanda became independent in 1962. Many Tutsi fled the country, going mainly to neighboring Burundi, Uganda, and the Congo (now the Democratic Republic of the Congo). Thousands of remaining Tutsi were slaughtered by the Hutu when violence broke out in 1963 and 1964. In the early 1970's many more Tutsi were forced to flee. In 1973 the army under General Juvenal Habyarimana overthrew the government. He outlawed all parties but his own and was elected president in 1978.

In 1990 a force of Tutsi exiles invaded the country, but the army, made up largely of Hutus, kept them in check. In 1994, after Habyarimana and President Cyprian Ntayamira of Burundi were killed when their plane was shot down by unknown attackers, the government collapsed. The Hutus turned on the Tutsis and massacred some 500,000. The Tutsi exile army then moved to rescue the Tutsis and succeeded in conquering the country. About a million Hutus were displaced, fleeing to neighboring countries as refugees. In 1996 many Hutu refugees returned to Rwanda. In 1998, Jean Kambanda, who served as Rwanda's Prime Minister during the 1994 massacre, was convicted of genocide by a United Nations tribunal and sentenced to life in prison.

Rwanda signed a peace accord with the Congo in July, 2002. Rwandan troops left the Congo by October of that same year. A new constitution was approved by voters in 2003.