Slavery developed for over four centuries into a major industry especially in the US that, in the 18 century, drove and powered the world economy.
Owners of large properties in the colonial era only wanted profit and would have enslaved anybody to increase their revenue, irrespective of their origin or colour.
This trade was further reinforced by the racist ideology that considered the superiority of whites over the blacks.
According to the UNESCO, the slaves were considered as property that was moveable and had no rights of possession or contract.
The available evidence points one to the conclusion that is in fact a combination of both elements and the time and place of origin does not really matter.
As is well known, slavery is legally not allowed anymore in almost all the countries around the world.
They had another standard – civilized and barbarian – and you could have white skin and be a barbarian, and you could be black and civilized.
During the 17 century, there was a great inflow of poor white people from Europe who came to America to work as indentured servants: there was not only a great rise in the population of Europe, there was also a move to relocate people who were considered to be undesirable in their own country such as vagabonds, convicts, dissenters, poor or prisoners of war.
This fact is seen from the cruelly treated indentured servants they had during those times from Europe or even from their own country.
Some slave owners even tried to justify the enslavement of black people by quoting the Bible.