Ancient Greece had a lot of cities, and they all seems to be wildly different in culture, society, language, etc. Is there any actual major common element between all/most of these cities apart from the fact that they're all one country today?

by DavidChengYueh

gynnis-scholasticus

I can recommend some earlier threads on the topic by the venerable u/Iphikrates. He has written about what made Ancient Greeks "Greek", about Greekness and Macedon, and you might also be interested in this answer about Greeks fighting each other