The shortage of labour. The failure to find alternative sources of labour. The legal position. Racial attitudes.
Slavery operated in the first civilizations (such as Sumer in Mesopotamia, which dates back as far as 3500 BCE). Slavery features in the Mesopotamian Code of Hammurabi (c. 1860 BCE), which refers to it as an established institution. Slavery was widespread in the ancient world.
In 1501, shortly after Christopher Columbus discovered America, Spain and Portugal began shipping African slaves to South America to work on their plantations. In the 1600s, English colonists in Virginia began buying Africans to help grow tobacco.
The First Africans in Virginia Landed in 1619. It Was a Turning Point for Slavery in American History—But Not the Beginning.