The island of Zanzibar, part of the commerce-heavy Swahili Coast, has been home to humans for about 20 thousand years after people managed to find their way to it from Africa. Few records exist referring to Zanzibar until around the death of Muhammed in 632 AD. But its location made it a prime spot for the trade routes of the Arabs, Swahili, Indians, and Persians; traders and others from all these migrated to Zanzibar. The island also made a convenient base for slave raids along the coast of east Africa.
Da Gama’s visit in 1498 intrigued folks back home; in 1503 or so, Zanzibar became part of the Portuguese Empire when a small military expedition landed, demanded and received tribute from the local sultan in exchange for peace. But the Portuguese were rather lax landlords, for when a British ship stopped by in 1591 the captain found no Portuguese fort or garrison, only a feitoria.
No doubt part of the Portuguese interest in keeping things peaceful was the cultivation of spices on the islands: cloves, vanilla, cinnamon, and nutmeg among others less valued. Slaves worked the great plantations that sprang up across the colony. Meanwhile, all sorts of trading ships were sailing in and out of the harbors, both European and Asian. The sultans continued to rule from Stone Town (the heart of what is now Zanzibar City) for the next two centuries, so long as the Portuguese got their cut.
But this semi-autonomy came to an end when the British got the wind up over the Portuguese and Arab slave trade. After several decades of negotiations, threats and occasional violence, the Anglo-Zanzibari Treaty in 1873 ended the practice, and Zanzibar’s economy collapsed. The Portuguese pulled out and in 1890 Germany, the only other power with any interest in the region, officially recognized “the British protectorate” over Zanzibar. The protectorate would be unilaterally terminated by the United Kingdom in December 1963, and Zanzibar would join Tanganyika to form Tanzania.