The rise of Zanzibar was based on two major economic transformations. Firstly slaves became used for producing cloves and grains for export. Previously the slaves themselves were exported.
Secondly, there was an increased international demand for luxuries such as ivory. At the same time the price of imported manufactured gods was falling. Zanzibar took advantage of its strategic position to trade as far as the Great Lakes.
However this very economic success increasingly subordinated Zanzibar to Britain, with its anti-slavery crusade and its control over the Indian merchant class....