The Proto-Greeks probably arrive at the area now called Greece, in the southern tip of the Balkan peninsula, at the end of the 3rd millennium BCE, though a later migration by sea from eastern Anatolia, modern Armenia, has also been suggested The sequence of migrations into the Greek mainland during the 2nd millennium BCE has to be reconstructed on the basis of the ancient Greek dialects, as they presented themselves centuries later and is subject to some uncertainties.

There are at least two migrations, the first of the Ionians and Aeolians which results in Mycenaean Greece by the 16th century BCE, and the second, the Dorian invasion, around the 11th century BCE, displacing the Arcadocypriot dialects, which descend from the Mycenaean period.

Both migrations occur at incisive periods, the Mycenaean at the transition to the Late Bronze Age and the Doric at the Bronze Age collapse.There are some suggestions of three waves of migration indicating a Proto-Ionian one, either contemporary or even earlier than the Mycenaean.

This possibility appears to have been first suggested by Ernst Curtius in the 1880s.

In current scholarship, the standard assumption is to group the Ionic together with the Arcadocypriot group as the successors of a single Middle Bronze Age migration in dual opposition to the "western" group of Doric.