Ancient Greek phonology in eastern Greece north of the Peloponnese: in Thessaly, in Locris, Phocis, and southern Aetolia, and in Boeotia, a region close to Athens. Aeolic was carried to Aeolis, on the coast of Asia Minor, and the nearby island of Lesbos. By the time of Ancient Greek, the only Aeolic dialects that remained in Greece were Thessalian and Boeotian. The Aeolic dialects of Greece adopted some characteristics of Doric, since they were located near Doric-speaking areas, while the Aeolian and Lesbian dialects remained pure. Boeotian underwent vowel shifts similar to those that occurred later in Koine Greek, converting to , to
Ancient Greek phonology and this cluster underwent metathesis early in the Ancient Greek period. Metathesis is likely in this case; clusters of a voiced stop and , like , do not occur in Ancient Greek, since they change to by assimilation (see below), while clusters with the opposite order, like , pronounced , do occur. Ancient grammarians, such as Aristotle in his "Poetics" and Dionysius Thrax in his Art of Grammar, categorized letters () according to what speech sounds ( 'elements') they represented. They called the letters for vowels ('pronounceable', singular ); the letters for the nasals, liquids, and , and the letters