East African Slave Trade
Slave shipments across the Indian Ocean began before the Christian Era. As a wealthy Muslim civilization developed during the eighth century A.D., Arab traders began to send a steady stream of slaves from East African ports to the markets of Turkey, Arabia, India, and Persia. The Arab traders were more brutal than Europeans and knew far less about how to keep the slaves from dying of disease. For every five blacks captured in the African interior, perhaps only one reached the Middle East markets.
In the 19th century, the island of Zanzibar and the port of Kilwa on the mainland slightly to the south became the largest African shipping points for the trade. Arab slavers began to penetrate farther and farther inland, as far as Uganda and the Congo, in search of slaves.
British pressure finally forced Zanzibar's ruler, in 1873, to close his slave markets and forbid the export of slaves from his dominions. However, enforcement was not easy, until an agreement was made by the great powers in 1890 to police the coast effectively. As late as the 1970's, the United Nations was receiving complaints of a thriving trade in black slaves in East Africa.