More than 120 ethnic groups are represented in Tanzania. Most groups are characterized by some internal variation in language and culture. The largest ethnic group, the Sukuma, represents nearly 13% of the total population; the remaining large groups represent under 5% each. Ethnicity continues to reflect geographic area. During colonial rule, administrative subdivisions had often been drawn along ethnic lines; this situation has continued after independence despite the government's genuine efforts to downplay ethnic considerations. Less than 1% of Tanzania's population is made up of non-Africans, including Europeans, Asians, and Arabs.

The two largest ethnic groups in Tanzania are linguistically and culturally closely related. The traditional homelands oftheSukuma and Nyamwezi are in western Tanzania, south of Lake Victoria. Sukuma actually means "north" and it refers to "people of the north"; however, the Sukuma refer to themselves as Basukuma (plural) and Musukuma (singular). The Nyamwezi refer to themselves as Banyamwezi (plural) and Munyamwezi (singular). Both are Bantu-speaking peoples who in the past were agriculturists and cattle keepers. Most family farms are subsistence, but also surplus crops for cash. Also, before German rule, the Sukuma and Nyamwezi acted as middle-men in the trade with the Swahili on the coast. In pre-colonial times, there was a strong ruler, a king or mtemi, called Mirambo. He was great military leader and strategistwho between 1860-1884 was able to carve out a large empire through conquest and diplomacy among the Sukuma and Nymawezi. In post-colonial Tanzania, Mirambo became an important political symbol because he had been able to deal with Europeans from a position of strength.

The third largest ethnic group is the Chagga who live on the southern slopes of Mount Kilimanjaro. They are also a Bantu people who are primarily cultivators and cattle keepers. They grow Arabica coffee, which is their primary cash crop, and bananas, which is their staple food. Chagga brew beer from banana and eleusine. Today, land shortages have altered their economic structure. Many Chagga are now wage earners in large cities but still grow coffee as a cash crop. In pre-colonial times, the Chagga were governed by a system of chiefs, and these chiefs would often wage war against each other. The German exploited this by helping friendly chiefs and encouraging them to attack those the Germans deemed unfriendly.

Archeological evidence suggests the Swahili have inhabited the East African Coast since the 1st century AD. Arabic and Chinese medieval documents record the presence of a people involved in the long distance trade of ivory, slaves, gold, and grain in exchange for textiles, beads, weapons, and porcelain. The Swahili were, and are, an urban people living in "stone towns" up and down the coast and on Zanzibar island. The Swahili became Muslim around the 12th century. They are also well known for their ship building and navigation; their dhows have participated in trade on the Indian Ocean for centuries. Wood carving, especially elaborate doors and furniture, as well as making gold and silver jewelry are Swahili industrial arts. Poetry is an important part of Swahili art. Poetic chronicles record history and today poetry is composed for weddings, civic occasions, and for competitions broadcast on radio and television. Swahili is a Bantu language that has borrowed from Arabic and English. Swahili culture has been at the crossroads of Africa, India, Arabia and Europe. Their language reflects this, as well as their folklore, which reveals Islamic influence, and their food, which shows African, Middle Eastern and Indian influences.

The Shirazi are a group of people who also live on the Tanzanian coast, mainly on the islands of Zanzibar and Pemba. They claim descent from an Iranian prince who long ago fled to Africa. The legend of their migration starts with Ali ben Sultan Hasan of Shiraz in what is today Iran. Around 975 AD he had a dream that a giant rat with jaws of iron destroyed the foundation of his palace. He interpreted the dream as an omen of evil befalling his house. Together with his family and faithful retainers, he set out on seven dhows. In a storm, they were separated and landed at seven different places on the coast. At these landing sites, Shirazi communities were established.

The Zaramo are a Bantu group that inhabit the area around Dar-es-Salaam and number around 200,000. They migrated to this area about 200 years ago because they were displaced from their homes by the Ngoni to the south and Kamba to the north. They settled in a very fertile area. In the 1800 they came into conflict with the Sultan of Zanzibar, and as a price of defeat they exacted a toll for all trade caravans going to and from the interior. Although they did not have a centralized government, the Zaramo managed to mobilize 5,000 men in 1874 to ensure that the Sultan of Zanzibar continue the payment of tribute. Today they are primarily cultivators growing fruit trees, cashew nuts, and rice. They also raise sheep, goats, chickens but not cattle. The Zaramo believe in one supreme being called Mulungu who was associated with rain. Each family was responsible for the veneration of their ancestors who could intercede with Mulungu.

The Makonde are one of the five largest ethnic groups in Tanzania, and they live in southern Tanzania and in Mozambique. Communication with this region is very difficult which has contributed to a strong sense of ethnic self-consciousness.This isolation also means that they have not been greatly influenced by colonial and post-colonial developments. They are known nationally for fiercely defending their culture, way of life, and land. However, the Makonde are best known internationally for their excellent wood carvings of family trees. The Makonde practice slash and burn agriculture growing maize, sorghum, and cassava. Politically, each Makonde village maintains a sense of indepedence. Each village will have a chief who inherited the position, but there is not an overall Makonde ruler or chief. Makonde still practice their traditional religion even though they have been in contact with Muslim traders for hundreds of years. Their religion centers around the veneration of their ancestors, which ties in with their family tree carvings that depict the older generation on the bottom supporting (literally and symbolically) later generations.