How did the geography of ancient greece impact the civilization

In today's world, greece separates asia and europe. Ancient greece was a prominent power made up of little city states, these city states waged war against each other at all times. When the persian wanted to invade europe, the greek stood proud all together. Quite some time later, Europe became a massive empire due to the romans taking place in the lands. We could say that the Greeks created that empire in some sorts due to the fact that the roman stayed unhindered for some time to actually develop. Same thing goes for islam. Today, nearly everywhere Islam is present, there is conflict and war. During the ascension of Islam, greece was in some sort of a shield, it absorbed all islamic toughts in Europe giving place to a growing Christian world. We may think Greece did nothing, yet it proved to be one factor of what Europeans are today, on both the cultural plan and the religious plan.