Scope of the trade[ edit ] A 19th-century European engraving of Arab slave-trading caravan transporting African slaves across the Sahara. African Zanj slaves[ edit ] The Arab slave trade, across the Sahara desert and across the Indian Ocean , began after Muslim Arab and Swahili traders won control of the Swahili Coast and sea routes during the 9th century see Sultanate of Zanzibar. These traders captured Bantu peoples Zanj from the interior in present-day Kenya , Mozambique and Tanzania and brought them to the coast. This trade accelerated as superior ships led to more trade and greater demand for labour on plantations in the region. Eventually, tens of thousands of captives were being taken every year. To meet the demand for menial labor, Bantu slaves bought by Arab slave traders from southeastern Africa were sold in cumulatively large numbers over the centuries to customers in Egypt , Arabia , the Persian Gulf , India , European colonies in the Far East , the Indian Ocean islands , Ethiopia and Somalia.