In 1698; Zanzibar fell under the control of the Sultanate of Oman. Until around 1890; the sultans of Zanzibar controlled a substantial portion of the East African coast; known as Zanj; which included Mombasa; Dar es Salaam; and trading routes extending much further inland; such as the route leading to Kindu on the Congo River.

The sultans developed an economy of trade and cash crops in the Zanzibar Archipelago with a ruling Arab elite. Ivory was a major trade good. The archipelago; also known as the Spice Islands; was famous worldwide for its cloves and other spices; and plantations were developed to grow them. The archipelago's commerce gradually fell into the hands of traders from the Indian subcontinent; whom Said bin Sultan encouraged to settle on the islands.

Zanzibar City was East Africa's main port for the slave market between Africa and Asia (including the Middle East); and in the mid-19th century as many as 50;000 slaves passed annually through the port. Sultan Barghash bin Said helped abolish the slave trade in the Zanzibar Archipelago after 1870. Pictures From History