Why are people racist?

The greek polises were city states that lived independently of each other and had their own laws and their own culture. those that were democratic were mostly based around direct democracy but not everyone had voting rights. sometimes there were kings but they would often get exiled if the people decided that they were getting too powerful. this was especially common in athens.the roman republic was a bit different. there was centralized government of all cities and territories and laws were made using a form of representative democracy, which means that there was a senate full of senators who made decisions for everyone. they would get chosen to those positions or earn them.the roman republic turned into the roman empire when it was established that the senate was corrupt and didn't care about people. then people started becoming emperors who usually ruled like dictators and there was no democratic decision making. this is the type of rule that we saw from caesar and those after him. this was also the type of rule when the roman empire divided and fell.