19世纪前期阿曼素丹国控制了波斯湾和东非沿海地区，利用地理位置优势在西印度洋从事奴隶贸易。同期，英国在西印度洋打击西方奴贩，造成阿拉伯人主导西印度洋奴隶贸易的局面。在印度商人的资助下，阿拉伯人将奴隶从东非大陆带往桑给巴尔和波斯湾，填补当地劳动力缺口。随着西方国家对桑给巴尔丁香、波斯湾珍珠和椰枣的需求不断增加，阿拉伯人从东非大陆引入更多奴隶。与此同时，阿拉伯人在西印度洋建立了一套稳定的奴隶管理体系，进一步推动奴隶贸易的发展，并于19世纪中期达到顶峰。19世纪后期，阿曼素丹国的分裂、奴隶逃亡现象的频发和英国加强打压阿拉伯人在西印度洋奴隶贸易中作用的力度，导致西印度洋奴隶贸易走向衰落。英国和德国借奴隶议题干涉东非事务，桑给巴尔素丹国及其东非领地沦为西方的保护国。
In the early 19th century，the Sultanate of Oman controlled the Persian Gulf and the east African coast and then used their geographical advantages to engage in the slave trade in the West Indian Ocean. In the same period，Britain cracked down on western slave traders in the Western Indian Ocean，resulting in the situation that Arabs dominated the slave trade in the Western Indian Ocean. With the help of Indian businessmen，Arabs brought slaves from East Africa to Zanzibar and the Persian Gulf to fill the local labor gap. Because of the increasing demand of western countries for Zanzibar cloves，Persian Gulf pearls and dates，Arabs introduced more slaves from East Africa. At the same time，the Arabs established a stable slave trade system in the Western Indian Ocean which further promoted the development of the slave trade，and resulted in slave trade reaching its peak in the mid-19th century. In the late 19th century，because of the division of the Sultanate of Oman，the frequent escape of slaves and Britain’s great efforts to crack down on the Arabs’ role in the West Indian Ocean Slave trade，the slave trade in the Western Indian Ocean declined. Because Britain and Germany intervened in East African affairs through the issue of slavery，Zanzibar Sudan and its territory in East African became western protectorate.
