Fossils found in East Africa suggest that protohumans roamed the area more than 20 million years ago. Recent finds near Kenya's Lake Turkana indicate that hominids lived in the area 2.6 million years ago.

Cushitic-speaking people from northern Africa moved into the area that is now Kenya beginning around 2000 BC. Arab traders began frequenting the Kenya coast around the first century A.D. Kenya's proximity to the Arabian Peninsula invited colonization, and Arab and Persian settlements sprouted along the coast by the eighth century. During the first millennium A.D., Nilotic and Bantu peoples moved into the region, and the latter now comprises three-quarters of Kenya's population.

The Swahili language, a mixture of Bantu and Arabic, developed as a lingua franca for trade between the different peoples. Arab dominance on the coast was eclipsed by the arrival in 1498 of the Portuguese, who gave way in turn to Islamic control under the Imam of Oman in the 1600s. The United Kingdom established its influence in the 19th century.

The colonial history of Kenya dates from the Berlin Conference of 1885, when the European powers first partitioned East Africa into spheres of influence. In 1895, the U.K. Government established the East African Protectorate and, soon after, opened the fertile highlands to white settlers. The settlers were allowed a voice in government even before it was officially made a U.K. colony in 1920, but Africans were prohibited from direct political participation until 1944.

From October 1952 to December 1959, Kenya was under a state of emergency arising from the "Mau Mau" rebellion against British colonial rule. During this period, African participation in the political process increased rapidly.

The first direct elections for Africans to the Legislative Council took place in 1957. Kenya became independent on December 12, 1963, and the next year joined the Commonwealth. Jomo Kenyatta, a member of the large Kikuyu ethnic group and head of the Kenya African National Union (KANU), became Kenya's first president. The minority party, Kenya African Democratic Union (KADU), representing a coalition of small ethnic groups that had feared dominance by larger ones, dissolved itself voluntarily in 1964 and joined KANU.

A small but significant leftist opposition party, the Kenya People's Union (KPU), was formed in 1966, led by Jaramogi Oginga Odinga, a former vice president and Luo elder. The KPU was banned and its leader detained after political unrest related to Kenyatta's visit to Nyanza Province. No new opposition parties were formed after 1969, and KANU became the sole political party. At Kenyatta's death in August 1978, Vice President Daniel arap Moi became interim President. On October 14, Moi became President formally after he was elected head of KANU and designated its sole nominee.

In June 1982, the National Assembly amended the constitution, making Kenya officially a one-party state, and parliamentary elections were held in September 1983. The 1988 elections reinforced the one-party system. However, in December 1991, Parliament repealed the one-party section of the Constitution. By early 1992, several new parties had formed, and multiparty elections were held in December 1992.

Moi was reelected for another 5-year term. Opposition parties won about 45% of the parliamentary seats, but Moi's KANU Party retained a majority of the legislature. Parliamentary reforms in November 1997 expanded political rights in Kenya, and the number of political parties grew rapidly. Moi won re-election as President in the December 1997 elections, and his KANU Party narrowly retained its parliamentary majority, with 109 out of 122 seats.

In December 2002, the people of Kenya elected Mwai Kibaki as the country’s third president. President Kibaki received 62 percent of the vote, and his 15-party group, the National Rainbow Coalition (NARC), also won 59 percent of the parliamentary seats.