Why did independent city-states develop in ancient?

Answer 1

They probably developed because of how isolated each community was because of the mountains in Greece.

Answer 2

Originally people lived by hunting and gathering. They lived in small groups probably like the pigmies of Africa of today. When they developed agriculture, they faced other people who would steal their crops. People had to defend their crops from outsiders. They needed to live in larger groups. By living in larger groups, they could store their crops and defend them and keep them safe from outsiders. As time passed, the places where they lived grew larger. The secure areas where they lived became bigger. The distance from their crops became a little greater. Finally it reached a limit. The distance people could walk from the city to work their fields and then return to the city before nightfall reached its limit. If anyone wanted to farm more distant land, they had to create a place to live a greater distance away. So the city states rose as a way to protect local farmers from marauding highway men.