The oldest Greek prose, including that of Heraclitus, Herodotus, Democritus, and Hippocrates, was also written in Ionic.

By the end of the 5th century BC, Ionic was supplanted by Attic, which had become the dominant dialect of the Greek world.

According to tradition, the ancestors of Ionians first set out from Athens, in a series of migrations, to establish their colonies on the coast of Asia Minor and the islands of the Cyclades, around the beginning of the Protogeometric period (1075/1050 BC).

The linguistic affinity of Attic and Ionic is evident in several unique features, like the early loss of /w/, or the merger of /ā/ and /ē/, as seen in both dialects.

The dialect was soon spread by Ionian colonization to areas in the northern Aegean, the Black Sea, and the western Mediterranean, including Magna Graecia in Sicily and Italy.

The most famous New Ionic authors are Anacreon, Theognis, Herodotus, Hippocrates, and, in Roman times, Aretaeus, Arrian, and the Lucianic or Pseudo-Lucianic On the Syrian Goddess.

[citation needed] Ionic acquired prestige among Greek speakers because of its association with the language used by both Homer and Herodotus and the close linguistic relationship with the Attic dialect as spoken in Athens.

[8] Eastern Ionic stands apart from both other dialects because it lost at a very early time the /h/ sound (psilosis) (Herodotos should therefore properly be called Erodotos).

An inkling of this may be witnessed in the language of Ephesian "beggar poet" Hipponax, who often used local slang (νικύρτας, σάβαυνις: terms of abuse; χλούνης, thief; κασωρικός, whorish) and Lydian loanwords (πάλμυς, king).

[12] Proto-Greek e, o > East/Central Ionic ei, ou:[note 1] compensatory lengthening after loss of w in the sequences enw-, erw-, onw-, orw-.