Greek colonisation refers to the expansion of Archaic Greeks, particularly during the 8th–6th centuries BC, across the Mediterranean Sea and the Black Sea.
The Archaic expansion differed from the Iron Age migrations of the Greek Dark Ages, in that it consisted of organised direction (see oikistes) away from the originating metropolis rather than the simplistic movement of tribes, which characterised the aforementioned earlier migrations. Many colonies, or apoikiai(Greek: ἀποικία, transl. "home away from home"), that were founded during this period eventually evolved into strong Greek city-states, functioning independently of their metropolis.