The so-called colonization movement lasted from mid 8th century BC approximately until the end of the 6th century BC. It resulted in the foundation of Greek cities in Sicily, in South Italy, along the southern coast of France and eastern coast of Spain, in the peninsula of Cyrenaica in North Africa, along the Thracian coasts, in the Hellespont and the Black Sea areas.

The main characteristics of colonization were: firstly, that it was an organized movement, whose starting point was a mother-city and secondly, that colonies -with the exception of emporia- constituted cities since their foundation and they usually reproduced the institutions of their mother-cities.

Economic interests played an important role in the evolution of colonization. Members of economically upper classes were pioneers, as far as the expansion of Greece beyond the Aegean region is concerned. Upper classes looked for "chremata" (things useful for exchange purposes), such as silver and gold, stretches of grain, houses and livestock, in regions outside the Greek mainland.

Greek colonists developed trade with their mother-cities, as well as with other cities and colonies in and out of the Greek world. Also, they did not hesitate to get in contact and create trade relations with their neighbouring indigenous peoples, where that was feasible of course (Herodotus, Historia 4.108.1-109.1). In Emporion of Catalonia, a colony founded by the inhabitants of Phocaea in Asia Minor, the Greek and the indigenous communities inhabited the same region (Strabo, Geographia 3.4.8). However, even though they were surrounded by a common fortification, they were separated by an interior wall.

In some cases, the Greeks subjugated the natives and at other times, non-Greek tribes chased the Greeks off their region. But, for the most part, a well-balanced coexistence had prevailed between colonists and indigenous peoples that inhabited the region. In very few cases, there was also a mixture of the two heterogeneous elements, as for example in Lipari Islands, in South Italy, where existed a community consisting of Rhodians and Cnidians. On one hand the natives' fear of Etruscan raids and on the other the lack of alternatives for the Greeks made the two groups unite. Originally, they maintained their cultural identity, but gradually as they cultivated joint tracts of land, they were assimilated (Strabo, Geographia 5.4.7).

Greek colonies functioned as trade centres for neighbouring indigenous populations. They provided the services of a big developed market, which was capable of assimilating large quantities of products -but mostly slaves- and in exchange supply large amounts of money -in particular after the 6th century BC- in the form of coins.
Greek colonists spread coinage to their local neighbours. Greek coins have been found in quite a few communities of indigenous tribes and they probably had greater value as a precious object rather than as money. It is known that coins made of cheap metal or having little value were widely used among indigenous tribes, as for example the dolphins of Olbia on the Black Sea.