I’ve been saying this for years, so it’s nice to see this out in the open. Behold:

Far from meaning the end of slavery as Western demand for enslaved persons fell, the 19th century saw slavery’s increase in West Africa as a different type of external demand arose. The abolition of the Atlantic slave trade north of the Equator in the first two decades of the 19th century transformed West African economies. It was one of the major factors in the series of economic crises and political revolutions that shaped West African politics until the advent of formal colonialism in the 1880s

This is from Toby Green, an excellent scholar of Africa in the UK.