For centuries before Europeans began visiting the west coast of Africa by ship, western kingdoms shipped slaves, gold, ivory, and other commodities to Europe and the Near East via overland trade routes. As Europeans, first the Portuguese, began their maritime trading excursions, they began to purchase slaves, mostly war captives at this point, from African leaders, and by 1500, Portuguese slave traders were importing an estimated 3,000 slaves per year to Europe. It is important to note here that African leaders were not selling "their own people" into slavery. West Africa, like Europe, featured a diverse array of ethnicities and polities, and, like Europeans, they felt no sense of unity.
Later in the sixteenth century, the growth of colonies in the New World fueled an increased demand for slaves. As demand increased, West African leaders struggled amongst each other to control the slave trade, which was very profitable for them, if devastating to the people who found themselves shipped across the Atlantic to labor in the new colonies. The Africans still dictated the terms of the trade at this point, and Africa became one of the hubs of a new Atlantic economy. Europeans largely traded weapons and luxury items, which carried great prestige, for slaves. Guns, in particular, hastened the slave trade in Africa just as it did in the American Southeast, where Indian peoples raided each other for slaves to sell to Europeans.
In the sixteenth century, Spain held the asiento, or the right to a monopoly on the European slave trade. Spanish ships brought hundreds of thousands of slaves to the Caribbean as well as to Central and South America. In time, European traders exercised increased dominance over the trade, often employing gangs of men to bypass local leaders in acquiring slaves, thus increasing their profits. They worked out of slave fortresses built up and down the coastline, and made few distinctions in ethnic origin in taking captives.
For much of the seventeenth century, the Dutch dominated the slave trade, but the English gained control in the latter part of the century and imported by far the most slaves in the eighteenth through the royally chartered Royal Africa Company. By the end of the century, slavers based out of Liverpool were carrying over 35,000 Africans a year across the Atlantic in the dreaded Middle Passage. By far most of these slaves wound up in Brazil, with the Caribbean being the second most frequent destination. Britain's colonies in North America, where physical conditions were slightly better, had a naturally increasing population and therefore received fewer slaves. Before the slave trade was outlawed, as all European nations did in the nineteenth century, European slavers had carried over eleven million slaves to the Americas. For over three centuries, slave labor was the foundation of the thriving Atlantic economy.