Origin and history of Ionian

1590s, "of Ionia," the districts of ancient Greece inhabited by the Ionians, one of the three (or four) great divisions of the ancient Greek people. The name (which Herodotus credits to an ancestral Ion, son of Apollo and Creusa) probably is pre-Greek, perhaps related to Sanskrit yoni "womb, vulva," and a reference to goddess-worshipping people. As a noun from 1560s.

Ionia included Attica, Euboea, and the north coast of the Peloponnesus, but it especially referred to the coastal strip of Asia Minor, including the islands of Samos and Chios. The old Ionic dialect was the language of Homer and Herodotus, and, via its later form, Attic, that of all the great works of the Greeks. The name also was given to the sea that lies between Sicily and Greece, and the islands in it (1630s in English in this sense). The musical Ionian mode (1844) corresponds to our C-major scale but was characterized by the Greeks as soft and effeminate, as were the Ionians generally.

The Ionians delighted in wanton dances and songs more than the rest of the Greeks ... and wanton gestures were proverbially termed Ionic motions. [Thomas Robinson, "Archæologica Græca," 1807]