From around 800 BCE, ancient Greek city-states, most of which were maritime powers, began to look beyond Greece for land and resources. As a consequence, they founded colonies across the Mediterranean. Trade was usually the first step in the colonization process and then, after local populations were subdued or included within the colony, cities were established.
This is a companion discussion topic for the original content at https://www.worldhistory.org/Greek_Colonization/.