Starting in the eighth century BCE, the Greek city-states built colonies throughout the Aegean, Mediterranean, and Black Seas for the purpose of trade, acquisition of resources, and relief from population growth, famine, and drought.
The Greeks established colonies in Sicily, southern Italy, Egypt, and the Middle East. The colonies in Egypt and the Middle East extended trade routes to the major civilizations in those areas. Later, Greece expanded into Thrace, the Hellespont, and the Bosporus along the Black Sea, and North Africa, and then farther into the western Mediterranean. One of the primary causes for Greek colonization was food. As the population of a polis (city) grew, the polis experienced trouble growing enough food for the population because of a lack of land, famine, or drought. They also wanted more food for trading purposes. The mother polis traded pots, oil, tools, or weapons for wood, metals, and food.
Some colonists were exiles. The majority of the colonists were males. Initially, a Greek colony was made up of people from a single polis. Their loyalty and ties to their polis of origin were not very strong. Instead, the colonists had a stronger loyalty to the person who had led them to the site of the new colony, the oikist. This leader brought fire from the original polis’s hearth to the colony to show its connection to the founding polis.
Upon founding of the colony, the oikist would be the leader of the city until his death. Before an expedition could set out for the chosen site, the oikist would visit the oracle at Delphi to see if the god Apollo approved of the new colony.
A suitable site for colonization needed to provide fertile land and good anchorage, and to be defensible. Once the colonists arrived at the site, they sacrificed to the gods and said prayers over the site. Colonists created a plan for distribution of land and the layout of the city. The new colony normally carried over the traditions, religion, and laws of its founding polis, and the two cities normally favored each other in trading.
Common imports were timber, metals, fabrics, grain, slaves, ivory and spices.
Source: Greek Colonization
Courtesy of Ancient World History