All events · Empire, Clearance and Removal

The East African and Indian Ocean Slave Trade and the Zanzibar Plantations

c. 1750–1900 · Sub-Saharan Africa

Displacement Sexual Violence Abduction (Children)

Displaced

1 million

The evidence is far weaker than for the Atlantic. Ralph Austen's conservative census, summarised by AP Central, has the East African coast exporting over 300,000 enslaved people in the nineteenth century, of whom about two-thirds remained in Africa on Zanzibar, the Zanzibari coastal possessions or in Somalia, with a further roughly 500,000 in the Red Sea trade drawn mainly from the Gulf of Aden region. EBSCO records approximately 600,000 people sold in the Zanzibar markets between 1830 and 1873, and a British estimate of 1895 that three quarters of the island's 200,000 inhabitants were still enslaved. Far fewer records were kept than in the Atlantic and abolitionist sources carry an evident bias, so all figures are estimates.

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What happened

From the late eighteenth century the Omani sultanate, which moved its capital to Zanzibar in 1840, built a plantation economy on the islands of Zanzibar and Pemba growing cloves with enslaved labour, and financed caravans that reached the Great Lakes and the eastern Congo. Captives taken in the interior were marched to Kilwa and Bagamoyo, sold in the Zanzibar market and either retained on the islands and the Swahili coast or shipped to Oman, the Persian Gulf, the Red Sea and western India. EBSCO records approximately 600,000 people sold at Zanzibar between 1830 and 1873. British pressure produced Sultan Barghash's decree of 1873 prohibiting the seaborne slave trade, the further decree of 1890 under Sultan Ali bin Said and the abolition decree of 6 April 1897; Michelle Liebst's study in the Law and History Review argues that the sultans' own reformist motives have been understated and British agents too readily credited as abolitionists. Abolition was slow in effect: only about a tenth of those eligible completed the required paperwork in the first year, since freedom had to be applied for and housing and income proved.

Parties

Omani and Swahili merchants and the Sultanate of Zanzibar organised slave raiding and trading from the East African interior for plantations on the coast and for markets across the Indian Ocean

Disputed

The volume of the East African and Red Sea trades is disputed, with abolitionist-era estimates now regarded as inflated in some accounts and as conservative in others; the extent to which the sultans of Zanzibar acted under British coercion rather than from their own policy is argued by Liebst against the standard narrative.

The denominator

No defensible denominator exists. Captives were taken across a vast and unenumerated interior stretching from the Great Lakes to the Congo basin and Lake Nyasa; the first population data for these regions are colonial estimates from the 1900s. Historians such as Ralph Austen and Patrick Manning reconstruct export volumes of roughly a million or more for 1750-1900, but only as flows, not as shares of a known base population.

Where the baseline comes from

Zanzibar slave trade — Wikipediaopen-edited
Arab slave trade — Wikipediaopen-edited

On the death toll

No toll can be established. Mortality on the caravan routes from the interior to the coast was described as very high by missionary and consular observers, notably David Livingstone, and mortality in the dhow crossings and in the barracoons was also high, but these accounts are impressionistic and were produced in the service of an abolitionist campaign. No registers exist from which deaths could be counted, and deaths in the raiding that supplied the caravans are wholly unquantified.

Documented forms of violence

Forced LabourSexual ViolenceAbduction of Children

The AP Central summary of Austen's work, EBSCO and Liebst's article document raiding and abduction in the interior, plantation labour on Zanzibar and Pemba, and the market in women and children for domestic service and concubinage across the Indian Ocean.