Ancient Greek was a pluricentric language, divided into many dialects. The main dialect groups are Attic and Ionic, Aeolic, Arcadocypriot, and Doric, many of them with several subdivisions. Some dialects are found in standardized literary forms used in literature, while others are attested only in inscriptions.
There are also several historical forms. Homeric Greek is a literary form of Archaic Greek (derived primarily from Ionic and Aeolic) used in the epic poems, the "Iliad" and "Odyssey", and in later poems by other authors. Homeric Greek had significant differences in grammar and pronunciation from Classical Attic and other Classical-era dialects.
The origins, early form and development of the Hellenic language family are not well understood because of a lack of contemporaneous evidence. Several theories exist about what Hellenic dialect groups may have existed between the divergence of early Greek-like speech from the common Proto-Indo-European language and the Classical period. They have the same general outline, but differ in some of the detail. The only attested dialect from this period is Mycenaean Greek, but its relationship to the historical dialects and the historical circumstances of the times imply that the overall groups already existed in some form.
Scholars assume that major Ancient Greek period dialect groups developed not later than 1120 BC, at the time of the Dorian invasion(s)—and that their first appearances as precise alphabetic writing began in the 8th century BC. The invasion would not be "Dorian" unless the invaders had some cultural relationship to the historical Dorians. The invasion is known to have displaced population to the later Attic-Ionic regions, who regarded themselves as descendants of the population displaced by or contending with the Dorians.
The Greeks of this period believed there were three major divisions of all Greek people—Dorians, Aeolians, and Ionians (including Athenians), each with their own defining and distinctive dialects. Allowing for their oversight of Arcadian, an obscure mountain dialect, and Cypriot, far from the center of Greek scholarship, this division of people and language is quite similar to the results of modern archaeological-linguistic investigation.
One standard formulation for the dialects is:
West vs. non-west Greek is the strongest marked and earliest division, with non-west in subsets of Ionic-Attic (or Attic-Ionic) and Aeolic vs. Arcadocypriot, or Aeolic and Arcado-Cypriot vs. Ionic-Attic. Often non-west is called East Greek.
Arcadocypriot apparently descended more closely from the Mycenaean Greek of the Bronze Age.
Boeotian had come under a strong Northwest Greek influence, and can in some respects be considered a transitional dialect. Thessalian likewise had come under Northwest Greek influence, though to a lesser degree.
Pamphylian Greek, spoken in a small area on the southwestern coast of Anatolia and little preserved in inscriptions, may be either a fifth major dialect group, or it is Mycenaean Greek overlaid by Doric, with a non-Greek native influence.
Most of the dialect sub-groups listed above had further subdivisions, generally equivalent to a city-state and its surrounding territory, or to an island. Doric notably had several intermediate divisions as well, into Island Doric (including Cretan Doric), Southern Peloponnesus Doric (including Laconian, the dialect of Sparta), and Northern Peloponnesus Doric (including Corinthian).
The Lesbian dialect was Aeolic Greek.
All the groups were represented by colonies beyond Greece proper as well, and these colonies generally developed local characteristics, often under the influence of settlers or neighbors speaking different Greek dialects.
The dialects outside the Ionic group are known mainly from inscriptions, notable exceptions being:
- fragments of the works of the poet Sappho from the island of Lesbos, in Aeolian, and
- the poems of the Boeotian poet Pindar and other lyric poets, usually in Doric.
After the conquests of Alexander the Great in the late 4th century BC, a new international dialect known as Koine or Common Greek developed, largely based on Attic Greek, but with influence from other dialects. This dialect slowly replaced most of the older dialects, although Doric dialect has survived in the Tsakonian language, which is spoken in the region of modern Sparta. Doric has also passed down its aorist terminations into most verbs of Demotic Greek. By about the 6th century AD, the Koine had slowly metamorphosized into Medieval Greek.
Related languages or dialects
Ancient Macedonian was an Indo-European language at least closely related to Greek, but its exact relationship is unclear because of insufficient data: possibly a dialect of Greek; a sibling language to Greek; or a close cousin to Greek, and perhaps related to some extent, to Thracian and Phrygian languages. The Macedonian dialect (or language) appears to have been supplanted by Attic Greek in the Hellenistic period. Recent epigraphic discoveries in the Greek region of Macedonia, such as the Pella curse tablet, suggest that ancient Macedonian might have been a variety of North Western Ancient Greek.