Tanzania is made up of 100 or so tribal groups of mainly Bantu origin. None of these groups comprise more than 10% of the population and this perhaps contributes to the tranquility the country has experienced. The most numerous groups are the Sukuma of Lake Victoria, Chaaga of Mount Kilimanjaro, Nyamwenzi of Tabora, Hehe of Iringa and the Gogo of Dodoma.
Arab and Persian influence is strong in Zanzibar. The interaction of Arabs and Bantu Africans has resulted in the Swahili language now widely spoken in Eastern and Central Africa. Those in the know say that the purest Swahili dialect is spoken in Zanzibar. Swahili is now the Lingua Franca of Tanzania although English is widely understood in urban centers.
Make sure to experience the traditional food at the coast and Zanzibar. This is quite good and is based on seafood and rice dishes. Food in the mainland is generally a little bit stodgy and less exciting. The most popular drink is a very decent brew known as Safari Lager. Tanzania music and dance is popular throughout Eastern Africa and this attests to its quality. The lyrics are usually in Swahili. Get to listen to some of it and this may even help improve on your Swahili.