Zanzibar
Zanzibar (; ; ) is a semi-autonomous region of Tanzania. It is composed of the Zanzibar Archipelago in the Indian Ocean, off the coast of the mainland, and consists of many small islands and two large ones: Unguja (the main island, referred to informally as Zanzibar) and Pemba Island. The capital is Zanzibar City, located on the island of Unguja. Its historic centre is Stone Town, which is a World Heritage Site.
Federacy
Tanzania is divided in 30 regions. Five of those regions together form Zanzibar. This island is a self-governing region. It elects its own president who has control over the internal matters of the island. Zanzibar was an independent sultanate and a British protectorate, while Tanganyika was a German "Schutzgebiet" until 1919, when it became a British mandate territory. The two were united in 1964, after a popular revolt against the Sultan of Zanzibar.