The Indian Ocean carried an old and continuous traffic in enslaved people that the arrival of European companies redirected rather than created. East Africans and Malagasy were shipped north to Arabia, the Persian Gulf and India; Portuguese Goa, Dutch Batavia and Ceylon, and later French Mauritius and Bourbon drew enslaved labour from Madagascar, Mozambique, Bengal, Arakan, Sulawesi and Bali; the Dutch East India Company both bought slaves and took them as war captives, as at Banda. The Arakanese and Portuguese raiding of Bengal in the seventeenth century, which supplied thousands of captives a year to Chittagong and Batavia, is among the better-documented episodes. Volumes are poorly recorded because much of the traffic was carried in small vessels by merchants who kept no registers surviving today, and because European company records document only part of it. Modern estimates come from Austen for the African trades and from Richard Allen for European slave trading within the ocean, and both authors present their figures as provisional.
Swahili coast, Omani, Yemeni, Indian and later Portuguese, Dutch and French merchants shipped enslaved Africans, Malagasy, Indians and Southeast Asians across the Indian Ocean to Arabia, Persia, India and the European colonies of the Indies and the Mascarenes
No single denominator exists. The trades drew captives from the East African interior, Madagascar, the Horn, South Asia and the Indonesian archipelago across three centuries, and none of these source regions was enumerated in the period. Estimates of the volume itself are contested and rest on scattered customs records and merchant accounts rather than the systematic shipping data available for the Atlantic.
No defensible total. Mortality in transit is documented episodically in Dutch and Portuguese company records — losses on Madagascar and Bengal voyages were sometimes very heavy — but the absence of comprehensive registers means no aggregate can be constructed.
Raiding for captives on the Bengal and Malagasy coasts, the holding of enslaved people in company and private hands at Batavia, Goa and the Cape, and the sale of women and children into domestic and sexual servitude are documented in Dutch East India Company and Portuguese records analysed by Richard Allen and others.
Tanzania, Comoros, Yemen, Madagascar, Indonesia, India, South Africa