The Atlantic slave trade was the transfer of Africans primarily from West Africa to parts of the Americas between the 16th and 19th centuries, a large part of the Columbian Exchange. About 10 million Africans arrived in the Americas on European boats as slaves. The journey that enslaved-Africans took from parts of Africa to America is commonly known as the "middle passage". Today, millions of people in North America and South America, including the vast majority of the populations in the countries of the Caribbean, are descended from these Africans brought to the New World by Europeans. Slavery was already widespread in Africa, where captives were taken in war.