Who benefitted economically from slavery?

It was a both way profit, the Americans through free labor and the African leaders through selling war captives.

Explanation:

The development of the trade

Portugal and Britain were the two most 'successful' slave-trading countries accounting for about 70% of all Africans transported to the Americas. Britain was the most dominant between 1640 and 1807 when the British slave trade was abolished.

b, the anti immigrant fervor