I can give you some information that might be useful.
Greece is located in a place that is distinguished by 1) mountains 2) islands and 3) peninsulas. All of this means that it's easy to defend the particular places, but it's also hard to attack them: this supports small city states rather than big, unified empire, similar to the one that was established on the Italic peninsula.
The location on the sea was also probably an economic benefit for the Greek: this meant good trade opportunities and the possibility of fishing.