There followed two great events that upset the dialectal distribution within the Greek world. First, about 1100 BCE the Dorian invasions brought speakers of West Greek southward, then into the Peloponnese, and finally into the Aegean.
Some pre-Dorian Greek populations were expelled from their homes and emigrated eastward to the west coast of Anatolia and to Cyprus. Others, who remained where they were, became more or less thoroughly Dorian in speech. It has long been thought that some of the features that West Thessalian and, even more, Boeotian (both of which are Aeolic) shared in the 1st millennium with West Greek can be attributed to “recent” influences; on the other hand, some Doric dialects of the 1st millennium (e.g., in Crete) show sporadic traces of features attributable to an Arcado-Cypriot substratum. The other subsequent event, which is of a different sort, was the great colonization movement that began in the 8th century BCE. Each group of emigrants took the speech of its mother city and planted it in the new foundation.
Thus, there developed side by side on the shores of southern Italy and Sicily a totally new grouping of Greek dialects—Euboean Ionic at Cumae; Laconian Doric at Tarentum and Heraclea; Achaean at Sybaris, Croton, and Metapontum; Locrian at Locri Epizephyrii; Corinthian Doric at Syracuse; and so on.
Toward the middle of the 1st millennium BCE, the geographic distribution of the dialects (insofar as they are known directly through inscriptions) is, briefly, as follows:
West Group (Doric in the widest sense)
(1) North-West Greek: Aetolia, Locris (colony—Locri Epizephyrii), Phocis,
(2) Saronic Doric: the territory of Corinth (colonies—Corcyra, Syracuse), the Megarid (colonies—Megara Hyblaea, Selinus, Byzantium), Eastern Argolid,
(3) Western Argolid,
(4) South-East Aegean Doric: Melos and Thera (colony—Cyrene), Cos, Rhodes (colonies—Gela, Acragas),
(5) Crete,
(6) Laconia (colonies—Tarentum, Heraclea), Messenia,
(7) Achaea (colonies—Ithaca, Sybaris),
(8) Elis.
Aeolic Group
(1) Boeotia,
(2) Thessaly,
(3) Lesbos and Asiatic Aeolis.
Arcado-Cypriot Group
(1) Arcadia,
(2) Cyprus,
(3) Pamphylia (mixed with West Greek and Aeolic).
Ionic-Attic Group
(1) Attica,
(2) Euboea (colonies—Catana, Cumae),
(3) Northern Cyclades,
(4) Asiatic Ionia (colonies—foundations in Pontus [Black Sea]).
Greek language - Alphabet, Dialects, Origins: The Mycenaean script dropped out of use in the 12th century when the Mycenaean palaces were destroyed, perhaps in connection with the Dorian invasions. For a few centuries the Greeks seem to have been illiterate. In the 8th century at the latest but...
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