Tanzania (), officially the United Republic of Tanzania (Swahili: Jamhuri ya Muungano wa Tanzania), is a country in eastern Africa within the African Great Lakes region. It borders Kenya and Uganda to the north; Rwanda, Burundi, and the Democratic Republic of the Congo to the west; Zambia, Malawi, and Mozambique to the south; and the Indian Ocean to the east. Mount Kilimanjaro, Africa's highest mountain, is in north-eastern Tanzania.
Some prehistoric population migrations into Tanzania include Southern Cushitic speakers who moved south from Ethiopia; Eastern Cushitic people who moved into Tanzania from north of Lake Turkana about 2,000 and 4,000 years ago; and the Southern Nilotes, including the Datoog, who originated from the present-day South Sudan–Ethiopia border region between 2,900 and 2,400 years ago. These movements took place at about the same time as the settlement of the Mashariki Bantu from West Africa in the Lake Victoria and Lake Tanganyika areas. They subsequently migrated across the rest of Tanzania between 2,300 and 1,700 years ago.European colonialism began in mainland Tanzania during the late 19th century when Germany formed German East Africa, which gave way to British rule following World War I. The mainland was governed as Tanganyika, with the Zanzibar Archipelago remaining a separate colonial jurisdiction. Following their respective independence in 1961 and 1963, the two entities merged in April 1964 to form the United Republic of Tanzania.The United Nations estimated Tanzania's 2016 population at 55.57 million. The population is composed of several ethnic, linguistic, and religious groups. The sovereign state of Tanzania is a presidential constitutional republic and since 1996 its official capital city has been Dodoma where the president's office, the National Assembly, and some government ministries are located. Dar es Salaam, the former capital, retains most government offices and is the country's largest city, principal port, and leading commercial centre. Tanzania is a de facto one-party state with the democratic socialist Chama Cha Mapinduzi party in power.
Tanzania is mountainous and densely forested in the north-east, where Mount Kilimanjaro is located. Three of Africa's Great Lakes are partly within Tanzania. To the north and west lie Lake Victoria, Africa's largest lake, and Lake Tanganyika, the continent's deepest lake, known for its unique species of fish. The eastern shore is hot and humid, with the Zanzibar Archipelago just offshore. The Kalambo Falls, located on the Kalambo River at the Zambian border, is the second highest uninterrupted waterfall in Africa. The Menai Bay Conservation Area is Zanzibar's largest marine protected area.
Over 100 different languages are spoken in Tanzania, making it the most linguistically diverse country in East Africa. The country does not have a de jure official language, although the national language is Swahili. Swahili is used in parliamentary debate, in the lower courts, and as a medium of instruction in primary school. English is used in foreign trade, in diplomacy, in higher courts, and as a medium of instruction in secondary and higher education, although the Tanzanian government is planning to discontinue English as a language of instruction altogether. Approximately 10 percent of Tanzanians speak Swahili as a first language, and up to 90 percent speak it as a second language.