Answer:
The term color line was originally used as a reference to the racial segregation that existed in the United States after the abolition of slavery . An article by Frederick Douglass which was titled "The Color Line" was published in the North American Review in 1881.
It was invented by the Sumerians, so it would be Sumer
Individualism, the other terms would better describe the Middle Ages
When merchants traveled between towns selling goods, they would have items from different places and cultures. The buyers of these merchants would be fascinated with the new items they had never seen before of different cultures, and so they would buy those items and spread them around until everybody knew about and became interested in other cultures. The cycle continued, causing more and more people to appreciate other cultures.