In: Economics
The notion of "races" originated from the European era of exploration, it has been pointed out. People had noted that for a long time, e.g. Sudanese looked different from Egyptians and both looked different from Greeks, who looked different from Germans. But this actually meant that people's behaviors, like the languages they spoke and the gods they worshiped, varied when you went from one location to another. As long as you walked around on property, the people would look pretty much like the last people you'd met in any location you visited, just like the next people you'd see, even though the end points of your journey had different average looks.
Classical civilisations from Rome to China tended to invest the most in family or tribal affiliation than the physical appearance of an individual. Societies also tended to equate physical attributes, such as hair and color of the eyes, with psychological and moral values, typically assigning the highest quality to their own citizens and lower values to the "other," either lower classes or outsiders.
The argument that physical variations between the different groups may be attributed to environmental causes was influential in ancient Greek and Roman conceptions of human diversity. While ancient peoples probably had no understanding of evolutionary theory or genetic diversity, they may define their conceptions of race as being maleable. Climate and geography were the principal environmental reasons for physical variation in the ancient period. Though thinkers acknowledged variations in physical characteristics between different groups in ancient civilizations, the general opinion was that all non-Greeks were barbarians.