A brief, dated history of Zanzibar.
The Swahili coast
For over a thousand years Zanzibar was a hub of Indian Ocean trade, where African, Arab, Persian and Indian peoples met and merged into Swahili culture. The mosque at Kizimkazi, dated to 1107, is one of the oldest Islamic buildings in East Africa.
Portuguese and Omani rule (1503–1890)
The Portuguese took control around 1503, until the Omani Arabs drove them out in 1698. In 1840 Sultan Said bin Sultan moved his capital from Oman to Zanzibar, making Stone Town a wealthy centre of the clove, ivory and slave trades. The slave market was finally closed in 1873.
Protectorate and the shortest war (1890–1963)
Zanzibar became a British protectorate in 1890. On 27 August 1896 a dispute over the throne sparked the Anglo-Zanzibar War — at around 38 minutes, the shortest war in recorded history.
Revolution and union (1963–today)
Zanzibar gained independence in December 1963. The Zanzibar Revolution of 12 January 1964 overthrew the sultanate, and in April 1964 Zanzibar united with Tanganyika to form Tanzania — while keeping its own government, identity and unmistakable island character.
Informational summary. Dates follow widely accepted historical consensus.