 By 1630, Africans had replaced the Tupani as the largest contingent of labour on Brazilian sugar plantations.This ended the European medieval household tradition of slavery, resulted in Brazil's receiving the most enslaved Africans, and revealed sugar cultivation and processing as the reason that roughly 84% of these Africans were shipped to the New World.As Britain rose in naval power and settled continental North America and some islands of the West Indies, they became the leading slave traders.