Sadly, racism does exist in the world today, but it seems that it was not such a problem when we go back in times, which then makes it even worse that we are in the predicament that we are right now.
If you check out the Roman Empire, then people that had a different color of skin were never discriminated against in any way. At no point were they regarded as being second class citizens and they were never blocked or barred from doing anything in life. Ancient scholars and historians also never mentioned anybody in a derogatory manner because of the color of their skin either and everybody was regarded as being equal.
At the same time, society had no sense of a stigma against a mixed-race relationship and there was certainly nobody frowning upon it as the couple went about their daily life. This form of racial harmony would not last though. The exact moment when things went awry is still up for debate, but there is no doubt that it did not start while the Roman Empire was in full swing.