"Tanzania, with an eastern seaboard on the Indian Ocean and a western border abutting several of East Africa's Great Lakes, is a medium-sized poor country. Though it is socially diverse, with about 125 ethnic groups, it has enjoyed general political stability and national unity for about 40 years in a region wracked by civil wars, often with ethnic dimensions, in neighboring Rwanda, Burundi, Uganda, the Democratic Republic of the Congo, and Mozambique. Tanzania is a union formed in 1964 between the mainland--a German colony and later a British protectorate formerly known as Tanganyika--and the islands of Zanzibar, Pemba, and several smaller islands. The islands, which remain semi-autonomous with their own president and parliament, are populated by peoples of mixed Arab and African descent, and almost all are Muslim. […] There has been a gradual increase in political pluralism, but the CCM remains dominant in government and parliament, and is periodically accused of subverting the aspirations of opposition parties. Opposition parties have reportedly on some occasions been denied rally permits, and their party members detained, intimidated, and harassed, notably during electoral periods, according to human rights groups."
CRS Report for Congress, RS22781