They could not find enough labourers locally, and so they began to use the same source of labour used in the sugar plantations of the Caribbean - slaves from Africa.
Slavery is a system in which human beings are owned and forced to work by their master.
Slaves can be bought and sold, and are denied all rights, even to have a say about what happens to their children. Slavery has existed throughout history, in societies as varied as those of Rome, China and Africa. Many kinds of people in history have been, at some time or another, both slaves and slave owners. But in the Americas there developed a system of slavery that was closely associated with race - almost always, the masters were white and the slaves black. The child of a slave mother was born into slavery, and generally a black person was assumed to be a slave until he or she could prove otherwise.