What natural land form in ancient Greece encouraged colonization and trade?

The numerous natural harbors along the coastline of ancient Greece facilitated colonization and trade. The mountainous terrain created isolated valleys and regions, which led to the establishment of independent city-states that often relied on maritime trade for resources. These harbors allowed for easy access to the sea, enabling Greeks to engage in commerce and establish colonies across the Mediterranean and Black Sea regions. This geographical advantage significantly contributed to the cultural and economic expansion of ancient Greek civilization.