The mountainous landscape of Greece was a very important factor in the evolution of the polis. Much of Greece is steeped with impassable mountains that make travel difficult. Consequently, the people of Greece developed politically independent of one another. Regionalism set in and the Greeks developed dozens of city-states that were autonomous. These city-states developed political systems that were remarkably different. The development of independent states led to cooperation and trade between the various city-states. It also led to rivalry and warfare at times.
The mountains also created another difficulty: finding arable land for food production. To remedy this, the Greeks established colonies throughout the Mediterranean Sea, particularly along the coasts. This created even further political diversity as the Greeks came in contact with foreign peoples that influenced all parts of their culture, including government.