<P> By the 18th century, the overwhelming number of black slaves was such that Amerindian slavery was less commonly used . Africans, who were taken aboard slave ships to the Americas, were primarily obtained from their African homelands by coastal tribes who captured and sold them . Europeans traded for slaves with the slave capturers of the local native African tribes in exchange for rum, guns, gunpowder, and other manufactures . </P> <P> The total slave trade to islands in the Caribbean, Brazil, Mexico and to the United States is estimated to have involved 12 million Africans . The vast majority of these slaves went to sugar colonies in the Caribbean and to Brazil, where life expectancy was short and the numbers had to be continually replenished . At most about 600,000 African slaves were imported into the United States, or 5% of the 12 million slaves brought across from Africa . Life expectancy was much higher in the United States (because of better food, less disease, lighter work loads, and better medical care) so the numbers grew rapidly by excesses of births over deaths, reaching 4 million by the 1860 Census . Slaves were a valuable commodity both for work and for sale in slave markets and so the policy of actively encouraging or forcing slaves to breed developed, especially after the ending of the Atlantic slave trade . From 1770 until 1860, the rate of growth of North American slaves was much greater than for the population of any nation in Europe, and was nearly twice as rapid as that of England . </P> <P> Slaves imported to the Thirteen colonies / United States by time period: </P> <Ul> <Li> 1619--1700--21,000 </Li> <Li> 1701--1760--189,000 </Li> <Li> 1761--1770--63,000 </Li> <Li> 1771--1790--56,000 </Li> <Li> 1791--1800--79,000 </Li> <Li> 1801--1810--124,000 </Li> <Li> 1810--1865--51,000 </Li> <Li> Total--597,000 </Li> </Ul>

What 3 european powers colonised and controlled north america