I think it probably originated with the Muslims since their religion allows for chattel slavery and since a lot of Northern Africa had been conquered by them.
And in Islam (Sunni) the Arab Muslims consider the non-Arab Muslims to be inferior.
The
diary of Christopher Columbus reveals that he was a pious man. And the Catholic Church spoke very favorably about him. But recently, historical revisionists began to unfairly attribute the bad actions of some of the other explorers to Christopher Columbus.
When the four hundredth anniversary of Christopher Columbusās discovery of America was observed in 1892, the atmosphere was one of celebration. Columbus was a brave and skilled navigator who had brought two worlds together and changed history forever. The Knights of Columbus even put his name forward for canonization.
A century later, the prevailing mood was far more somber. Now Columbus was accused of all kinds of terrible crimes, ranging from environmental devastation to cruelties that culminated in genocideā¦
ā Thomas E. Woods, Jr., Ph.D.
How the Catholic Church Built Western Civilization, p.133, 2005
There was a lot more good than bad from the colonization by the explorers. They brought Christianity which replaced a barbaric pagan religion. And our Lady of Guadalupe helped convert many natives in Mexico to the Catholic faith while Protestantism was leading Catholics away from the Church in Europe.
Further References:
Encyclical of Pope Leo XIII on the Columbus Quadricentennial
Apostolic Journey to Venezuela, Ecuador, Peru, Trinidad, and Tobago
Special Assembly for America of the Synod of Bishops