The United Republic of Tanzania is a nation in central East Africa bordered by Kenya and Uganda to the north, Rwanda, Burundi and the Democratic Republic of the Congo to the west, and Zambia, Malawi and Mozambique to the south. The country's eastern borders lie on the Indian Ocean.

The United Republic of Tanzania is a unitary republic composed of 26 mikoa (regions). The current head of state is President Jakaya Mrisho Kikwete, elected in 2005. Since 1996, the official capital of Tanzania has been Dodoma, where parliament and some government offices are located. Between independence and 1996 the major coastal city of Dar es Salaam had been the country's political capital. Today Dar es Salaam remains the principal commercial city of Tanzania and the de-facto seat of most government institutions. It is the major seaport for the country and its landlocked neighbours. The name Tanzania is a portmanteau of Tanganyika and Zanzibar. The two states united in 1964 to form the United Republic of Tanganyika and Zanzibar, which later the same year was renamed the United Republic of Tanzania.

Tanzania is probably one of the oldest countries ever to be known continuously inhabited areas on Earth; fossil remains of humans and pre-human hominids have been found dating back over two million years. More recently, Tanzania is believed to have been populated by hunter-gatherer communities, probably cushitic and Khoisan speaking people. About 2000 years ago, Bantu-speaking people began to arrive from western Africa in a series of migrations. Later, Nilotic pastoralists arrived, and continued to immigrate into the area through to the 18th century. Travellers and merchants from the Persian Gulf and Western India have visited the East African coast since early in the first millennium CE. Islam was practised on the Swahili coast as early as the eighth or ninth century CE. Claiming the coastal strip, Omani Sultan Seyyid Said moved his capital to Zanzibar City in 1840. During this time, Zanzibar became the center for the Arab slave trade.[10] Between 65% to 90% of the population of Arab-Swahili Zanzibar was enslaved. One of the most famous slave traders on the East African coast was Tippu Tip, who was himself the grandson of an enslaved African. The Nyamwezi slave traders operated under the leadership of Msiri and Mirambo.

The African population consists of more than 120 ethnic groups, of which the Sukuma and Nyamwezi, the Hehe and Bena, the Gogo, the Haya, the Makonde, the Chagga and the Nyakyusa have more than 1 million members. Other groups include the Pare, Shambaa (or Shambala), and Ngoni. The majority of Tanzanians, including such large ethnic groups as the Sukuma and the Nyamwezi, have Bantu origins. Groups of Nilotic or related origin include the nomadic Maasai and the Luo, both of which are found in greater numbers in neighboring Kenya. The Sandawe and Hadza speak languages of the Khoisan family peculiar to the people of the Kalahari in southern Africa.