Greeks lived in isolated communities.
geography
The ancient Greek cities were isolated from one another for two basic reasons. One was the hilly geography of Greece. This natural setting spawned several isolated communities. The second reason was that these communities grew into city-states, with the dominant community ruling the smaller ones. These city-states were concerned with their own problems and their own advancement and had little to do with each other unless it was for mutual defense or profit.
Before they settled, as nomads they raided farming communities for spoils so needed to be fighters. When they settled on the land as farmers they needed to defend their land against nomads, pirates and indeed other citiy-states, trying to pillage them.
Ancient Greek city states were isolated because much of Greece is islands or mountains.
Geography has a few effects on the Greeks and the world. Some of the effects are developments of ancient Egypt and having relationships with other city-states.
Because Greece had a lot of mountain ranges which prevented contact between city states.
The geographical setting of Greece.
The physical features that isolated Greek communities primarily included mountains and the sea. The rugged terrain of the mountainous landscape made land travel difficult and led to the development of independent city-states (poleis) rather than a unified empire. Additionally, the numerous islands and the coastline encouraged maritime trade and communication but also contributed to a sense of separation between communities. This geographic fragmentation fostered distinct local cultures and political systems among the Greeks.
Ancient Greeks settled where they did because of the land topography. They settled near water and areas that were easy to defend.
romasns greeks celts
The Mediterranean and Black Sea littorals.