Republic of Zanzibar and Pemba (commonly known as Zanzibar) is a sovereign state in East Africa. It comprises the Zanzibar Archipelago in the Indian Ocean, 25–50 km (16–31 mi) off the coast of the mainland, and consists of numerous small islands and two large ones: Unguja (the main island, informally referred to as Zanzibar), and Pemba. Zanzibar was once a separate state with a long trading history within the Arab world; it united with Tanganyika to form Tanzania in 1964 and but regained its independence in 1984 shortly after Doomsday. Zanzibar's main industries are spices and raffia. In particular, the islands produce cloves, nutmeg, cinnamon and pepper. For this reason, the islands, together with Tanzania's Mafia Island, are sometimes called the "Spice Islands".