BLOOMINGTON, Ind. -- The discovery of the São José, a Portuguese slave ship that sank in 1794 near Cape Town, South Africa, is “indeed a major discovery,” in part because no other slave vessel has been excavated that sank while carrying slaves, says Indiana University historian Pedro Machado, who researches Indian Ocean trade in the late 1700s and early 1800s.

The story of the ship, which sank off the Cape of Good Hope while carrying 400 slaves from Mozambique bound for Brazil, was revealed this week by the Slave Wrecks Project, a collaboration by the Smithsonian National Museum of African American History and Culture, Iziko Museums of South Africa and the George Washington University.

Machado said slave trading in the Indian Ocean had a long history and primarily involved Asian captives trafficked over short distances. Near the end of the 18th century, the Mozambique slave trade created a diaspora that linked Madagascar and the islands of Mauritius, Reunion and Comoros with markets in the Arabian Peninsula, the Persian Gulf and western India.

“The most important destinations for Mozambique slaves were the French islands where coffee producers and especially sugar planters developed a high labor demand,” Machado said. “However, from late in the 18th century, Brazilian slave merchants -- working through partnerships or family connections with Portuguese merchants in Mozambique -- began to sail around the Cape of Good Hope to Mozambique to trade for slaves.

“Partly as the result of lower purchasing costs and in response to abolitionist pressures and accommodations, Brazilian negreiros, or slave merchants, traded for slaves in large numbers from the 1780s and 1790s and well into the 19th century,” he said. “They were joined for a brief period also by Spanish merchants from Buenos Aires and Montevideo, with whom Brazilian merchants maintained commercial relationships.”

Machado said years following 1811 witnessed a dramatic increase in the slave trade as Brazil's rapidly emerging position as a major supplier of sugar and coffee to world markets necessitated the continued importation of large supplies of slave labor. From 1812 to 1831, close to 147,000 slaves left Mozambique for Rio, representing about 20 to 25 percent of all imports at the Brazilian port. Including the smaller and intermittent exports to Bahia and Recife, as many as 180,500 slaves may have been shipped to Brazil overall from Mozambique in these 20 years.

“The São José was one of the many vessels that carried these human cargoes thousands of miles along the Indian Ocean coast and across the southern Atlantic,” Machado said. “Its discovery unmasks the connected histories of slaving and stresses the need to develop an understanding of its broad dynamics that created a widespread diaspora of 'Mocambiques.’”

Machado, an associate professor of history in the IU Bloomington College of Arts and Sciences, was born and raised in Cape Town, South Africa. He compiled information on the slave trade from Mozambique to Brazil for the Trans-Atlantic Slave Trade Database. He is the author of "Ocean of Trade: South Asian Merchants, Africa and the Indian Ocean, c.1750–1850." He can be reached at [email protected].