Ancient Mediterraneans obviously knew of black people but didn’t think of them apparently as different from other exotic “races”, like, say, Germans or Indians. It was not the quasi-biological concept of today, not so much finished in any case.

Racism also arose from or at least within religious discrimination. When Europeans first looked for moral justifications of slavery of exotic peoples, being a “heathen” was usually the more common pretext. In fact the English of Cromwell enslaved under that pretext hundreds of thousands of Irish Catholics (http://www.kavanaghfamily.com/articles/2003/20030618jfc.htm). And this is just surely one example among many. Only with time would the religious pretext become a racial one.

I think the modern concept of race is born of a mixture of scientific mentality and colonialism that would soon become racism. It did not appear out of the blue when Colombus landed in Quisiqueya (modern Hispaniola). In fact Colombus was surely very familiar with the existence of Black people with whom he must had contact or at least heard of when he was in Portugal (and there is a theory that claims that he was personally involved in the early slave trade in West Africa).

The conception of race is truly in the eyes of the beholder.

I certainly agree with this largely. It is mainly a social construct. There is some biological base but it’s very limited.

The best history books I have read agree with the bit, “was first recognized when the Europeans came over to America” but claim it was because Americans (and Europeans who provided the transport) felt obliged to justify their kidnapping of another group of people to work the intensive farming methods they were developing there.

The idea that races can be placed along a hierarchy of intelligence, say, is completely ridiculous anyway. Even if the average intelligence (however we might be able to measure that in any meaningful way) of one race is higher than in another there will be many people in the so-called inferior race who will be more intelligent than many people in the so-called superior one.

As you say the idea is simply to, “create a social hierarchy that is visible or easily identified”.