Tanzania is the cradle of mankind, for it was here in the Olduvai Gorge that Dr. Louis Leakey discovered the fossilized remains of Zinjanthropus calculated to be 1.75 million years old, the forerunner of modern man. South of Olduvai Gorge, a trail of hominid foot prints 3,600,000 years ago were discovered at Laoteli only 30 kilometers from Olduvai Gorge.

Tanzania is home of about 126 African tribes, the majority being of Bantu origin who migrated into Tanzania from West and Central Africa. While in Tanzania, they assimilated most of the people of Khoisan and Cushitic origin who had been there since the 3rd and 1st centuries BC respectively. Very few groups of people of these origins (Khoisan and Cushitic) remain in Tanzania today.

Besides peoples of Bantu, Cushitic and Khoisan origin, there are also groups of Nilotic origin the most famous being the Maasai. These are said to have settle in Tanzania in the 1st century AD. On the other hand, the Ngoni tribe, fleeing from "mfecane" (the times of troubles) brought about by the Zulu expansion under their famous King, Shaka, entered southwestern Tanzania in 1840 and defeated the Fipa who moved to northwestern Tanzania.

Arabian merchants visited the Tanzanian Coast 2000 years ago and later settled in Zanzibar around 7th century AD. They established trade routes into the interior and in so doing helped to spread the Arab influenced culture and language of the coast : Swahili culture and language.

The Portuguese established temporary settlements in the 16th century, and a relic of a Portuguese Fort, "Geresa" built in 1505 is in Kilwa. In the late 17th century, however, the Portuguese were supplanted by the Omanis who established trade in ivory and slaves. Ivory was in great demand in India, where married women were expected to wear ivory bangles which were buried with them when they died. Ivory trade was also established in the 18th century with Japan where it was required for production of "netsukes" (ivory buttons used to suspend objects from a belt). Slaves were used to carry ivory to the coast but were also required for clove plantations in Zanzibar and in sugar plantations in Mauritius. Other slaves were exported to the Persian Gulf, Europe and Americas.

The scramble for Africa by the European powers at the end of the 19th century led to the occupation of the mainland by Germany despite resistance by leaders such as Abushiri of Pangani, Mkwawa of Iringa, and Kinjeketile of Rufiji. The latter led the famous Maji maji uprising of July 1905. Zanzibar became a British Protectorate. After World War I, Germany was forced to surrender mainland Tanzania to British rule. The mainland (then known as Tanganyika) became independent in 1961 and Zanzibar in 1963. In 1964, Tanganyika and Zanzibar united to form United Republic of Tanzania.