Question

Why did independent city states develop on the Greek peninsula

Answer 1

"The differences between Athens and Sparta eventually led to war between the two city-states. Known as the Peloponnesian War (431-404 B.C.E.), both Sparta and Athens gathered allies and fought on and off for decades because no single city-state was strong enough to conquer the others."

According to ushistory.org

Answer 2

Rugged terrain limited trade and communication among groups of people in Greece.