How did the geography of Greece isolate their city-states?

The mountains, oceans, islands, and atmosphere confined isolated and separated Greece into little gatherings that became city-states

so they can differentiate themselves from others as they saw themselves as the superior race. the star was basically a symbol that meant you are a less of a person than i am because of my race. the star was also degrading for those who had to wear it because they were aware of this and the nazis used the notion to make them feel less like a person.