These patterns held considerable implications for the ethnolinguistic composition of the illegal slave trade. The mix of peoples in the Upper Guinea trade continued to be highly diverse in the illegal era. The largest group was Mende, but Koronko, Mandingo, Susu, Temne, and Fula were well represented. These six groups made up 80 percent of a sample of one thousand captives taken from Galinhas (Guinea-Bissau) and Rio Pongo (Guinea) in the 1820s and 1830s; three-quarters of these captives came from areas less than 150 miles from the coast. In the eighteenth century, peoples from the middle and upper regions of the Gambia and Senegal rivers would have been much more heavily represented.
In the Bight of Benin, Yoruba peoples, scarcely noticeable in an earlier era, dominated those passing through Whydah and Lagos, with some Hausa and Nupe among them. The counterparts to the Yoruba in the Bight of Biafra were Igbo peoples, perhaps accounting for as much as 60 percent of deportees from the region, but in this case the pattern was not new. Ibibio and the numerous small ethnic groups of the Niger Delta made up the remainder. Further east, the Cameroons Highlands was almost the exclusive source of slaves leaving from what is now the Republic of Cameroon.
New research on the huge West-Central Africa region suggests that the old picture of long-distant trade networks and the central importance of the Lunda Empire (northeastern Angola and western Congo) is in need of revision. Data from slave registers in the Portuguese colonies and from registers of liberated Africans in Havana and Sierra Leone indicate that the majority came from areas much closer to the coast than was previously thought. Overall, there seems to have been a shift toward the coast as the source for captives in the nineteenth century.
One further pattern to emerge after 1800 was an increase in the share of Muslims, almost all of them passing through ports located in the Bight of Benin, such as Lagos and Whydah, and comprising mainly Hausa and Yoruba. A preliminary analysis of a large database of Africans (including their names) who were taken off slave ships by British naval cruisers between 1821 and 1841 and liberated in Sierra Leone and Havana suggests that one-fifth of those leaving the Bight of Benin were Muslims, many of them women.