The best-known triangular trading systems were across the Atlantic Ocean, especially the Atlantic slave trade, which lasted from the late 16th to early 19th centuries. During this time, European countries such as Britain, Spain and France had colonies in the Americas and Africa. The ships carrying slaves, crops and manufactured goods between West Africa, the Caribbean and American colonies and the colonial powers in Europe. The use of African slaves was very important to growing colonial cash crops, which were exported to Europe. European goods, in turn, were used to buy African slaves, which were then brought west from Africa to the Americas to work on the crops. The middle passage of the triangular trade refers to the transportation of the slaves to America.