We'll never know exactly how Greece came to create colonies in Asia Minor and in southern areas of Italy, Megale Hellas, known better by the Latin name of Magna Graecia. Here is the modern theory followed by what the ancient Greeks thought had happened.

The essence of what we think happened is that a Dark Age invasion of a people known as Dorians swept down from the North, settling first in the Corinthian Gulf and the northwest Peloponnese, then the south and east, and the islands of Crete, Rhodes, and Kos. These Dorians pushed the native Greeks out of their homelands. Eventually some mainland Greeks migrated to Ionia.

The ancient Greeks had their own explanation of the Dorian Invasion....

Ancient Version of the Dorian Invasion

Thucydides on the Greek Colonies

"Sixty years after the capture of Ilium, the modern Boeotians were driven out of Arne by the Thessalians, and settled in the present Boeotia, the former Cadmeis.... Twenty years later, the Dorians and the Heraclids became masters of Peloponnese; so that much had to be done and many years had to elapse before Hellas could attain to a durable tranquillity undisturbed by removals, and could begin to send out colonies, as Athens did to Ionia and most of the islands, and the Peloponnesians to most of Italy and Sicily and some places in the rest of Hellas."

- Thucydides

Greeks in Asia Minor During the Trojan War

Ionian Settlements



Sources:

[URL = < vislab-www.nps.navy.mil/~fapapoul/history/dorians.html >]

Carlos Parada Heraclides

[www.perseus.tufts.edu/GreekScience/Students/Ellen/EarlyGkAstronomy.html] Early Greek Astronomers

Ionians mingled with Lydians and Persians and sea-faring people.

Ionians mingled with Lydians and Persians and sea-faring people. The Question of a Dorian Invasion

Thomas Martin Overview of Greek History in this section addresses both the question of the invasion and Greek chronology.

Homeric Geography