A chronology of key events:
1498 - Portuguese explorer Vasco da Gama visits Tanzanian coast.
1506 - Portuguese succeed in controlling most of the East African coast.
1699 - Portuguese ousted from Zanzibar by Omani Arabs.
1884 - German Colonisation Society begins to acquire territory on the mainland.
1886 - Britain and Germany sign an agreement allowing Germany to set up a sphere of influence over mainland Tanzania, except for a narrow piece of territory along the coast which stays under the authority of the sultan of Zanzibar, while Britain enjoys a protectorate over Zanzibar.
1905-06 - Indigenous Maji Maji revolt suppressed by German troops.
1916 - British, Belgian and South African troops occupy most of German East Africa.
1919 - League of Nations gives Britain a mandate over Tanganyika - today's mainland Tanzania.
1929 - Tanganyika African Association founded.
1946 - United Nations converts British mandate over Tanganyika into a trusteeship.
1954 - Julius Nyerere and Oscar Kambona transform the Tanganyika African Association into the Tanganyika African National Union.
1961 - Tanganyika becomes independent with Julius Nyerere as prime minister.
1962 - Tanganyika becomes a republic with Mr Nyerere as president.
1963 - Zanzibar becomes independent.
1964 - Sultanate of Zanzibar overthrown by Afro-Shirazi Party in a violent, left-wing revolution; Tanganyika and Zanzibar merge to become Tanzania with Mr Nyerere as president and Afro-Shirazi leader Abeid Amani Karume as vice-president.
1967 - Mr Nyerere issues the Arusha Declaration, which launches drive for socialist economic self-reliance.
1977 - The Tanganyika African National Union and Zanzibar's Afro-Shirazi Party merge to become the Party of the Revolution, which is proclaimed to be the only legal party.
1978 - Ugandans temporarily occupy a piece of Tanzanian territory.
1979 - Tanzanian forces invade Uganda, occupying the capital, Kampala, and help to oust President Idi Amin.
1985 - Mr Nyerere retires and is replaced by the president of Zanzibar, Ali Mwinyi.
1992 - Constitution amended to allow multi-party politics.
1995 - Benjamin Mkapa chosen as president in Tanzania's first multi-party election.
1998 August - Al-Qaeda Islamist terror group bombs US embassies in Tanzania and Kenya.
2000 - Mr Mkapa elected for a second term, winning 72% of the vote.
2001 January - At least 31 people are killed and another 100 arrested in Zanzibar in protests against the government's banning of opposition rallies calling for fresh elections; government sends in troops.
2001 March - Governing Chama Cha Mapinduzi and main Zanzibari opposition Civic United Front agree to form joint committee to restore calm and to encourage return of refugees from Kenya.
2001 April - Tens of thousands of opposition supporters march through the commercial capital, Dar es Salaam, in the first major joint demonstration by opposition parties in decades.
2001 July - Huge new gold mine, Bulyanhulu, opens near northern town of Mwanza, making Tanzania Africa's third largest producer of gold.
2001 November - Presidents of Tanzania, Uganda and Kenya launch regional parliament and court of justice in Arusha to legislate on matters of common interest such as trade and immigration.
2001 December - Britain approves controversial deal to sell military air traffic control system to Tanzania. Critics say it is a waste of money.
2005 March-April - Political violence in semi-autonomous Zanzibar ahead of voter registration for October poll.
2005 October - Governing Chama Cha Mapinduzi wins Zanzibar elections. Opposition Civic United Front claims vote-rigging and announces an indefinite boycott of Zanzibar's parliament.
2005 December - Jakaya Kikwete, foreign minister and ruling Chama Cha Mapinduzi candidate, wins presidential elections.
2006 August - The African Development Bank announces the cancellation of more than $640m of debt owed by Tanzania, saying it was impressed with Tanzania's economic record and the level of accountability of public finance.
2008 January - Central Bank Governor Daudi Ballali is sacked after an international audit finds the bank made improper payments of more than $120m (£60m) to local companies.
2008 February - President Kikwete dissolves cabinet following corruption scandal which forced the prime minister and two ministers to resign.
2009 November - Main opposition party in Zanzibar, Civic United Forum, ends five-year boycott of the island's parliament ahead of upcoming elections.
East African Common Market
2010 July - Tanzania joins its neighbours in forming a new East African Common Market, intended to integrate the region's economy.
2010 September - President Kikwete says construction of highway through Serengeti game reserve will go ahead, despite criticism from environmental experts.
2011 January - Two killed as police try disperse demonstrators demanding release of Chadema opposition party leader Freeman Mbowe, detained ahead of a rally against government corruption.
2011 July - British arms and aircraft firm BAE Systems admits setting up sham compensation arrangements worth £8m for the sale of an overly-complex air-traffic control system, and agrees to pay Tanzania £30m in compensation.
2012 March - The Statoil and Exxon Mobil oil exploration companies make major discovery of gas reserves off the coast of Tanzania.
2012 May - President Jakaya Kikwete sacks six ministers after the inspector of public finances notes the "rampant misuse of funds" in at least seven ministries. The ministers of finance, energy, tourism, trade, transport and health lose their jobs.
2012 August - Tanzania confirms 36 Iranian oil tankers have been using Tanzanian flags to evade US and EU economic sanctions on Iran's crude oil exports. The US warns Tanzania that it could face sanctions unless the flag operation stops.
2013 December - Four cabinet ministers are sacked over allegations of human rights abuses during a campaign against ivory poaching.
2015 April - Referendum on a new constitution is postponed after delays in registering voters.
2015 November - Works Minister John Magufuli of the governing Chama Cha Mapinduzi wins presidential election by large margin over former prime minister Edward Lomassa.
2016 April - Tanzania and Uganda agree to build East Africa's first major oil pipeline.
2017 February - Government bans several private health centres from providing HIV and AIDS-related services, accusing them of promoting homosexuality.
The Mwanahalisi newspaper becomes the second paper to be banned in recent months. Rights groups says press freedom is under increasing threat.
2017 October - Police detain a group of foreign lawyers discussing whether to challenge a government decision to limit the provision of health services which allegedly promote homosexuality.
2018 November - Authorities deploy army to buy cashew nuts from farmers to solve a row over prices.Major donor Denmark suspends aid over anti-gay campaign.
2020 October - President Magufuli wins re-election by a large margin, amid opposition allegations of fraud.
2021 March - President Magufuli dies, and is succeeded by Vice-President Samia Suhulu Hassan.