The region was of considerable importance in ancient times, for it was there that Greek settlers established colonies before 1000 B.C. These colonists were called Ionians, and tradition says that they fled to Asia Minor from the mainland of Greece to escape the invading Dorians. Athens claimed to be the mother city of all the Ionian colonists, but modern scholars believe that the Ionians were actually a mixed group (mainly from Attica and Boeotia) and that after migrating they were further mixed by intermarriage with native groups such as the Carians. Nevertheless, they spoke the same distinctive form of Greek that was spoken in Attica and Euboea, and their culture was always distinguished from that of the Dorians and Aeolians.

There came to be 12 major cities—Miletus, Myus, Priene, Sámos, Ephesus, Colophon, Lebedos, Teos, Erythrae, Khíos, Clazomenae, and Phocaea. A religious league (which reached its full power in the 8th cent. B.C.) was formed, with its center at the temple of Poseidon near Mycale. Smyrna, originally an Aeolian colony, later joined the league. The fertility of the region and its excellent harbors brought prosperity to the cities. Traders and colonists traveled the Mediterranean as far west as Spain and up to the shores of the Black Sea.

In the 7th cent. B.C. the Ionian cities were invaded by the Cimmerians, but they survived. In the same century Gyges, king of Lydia, invaded, but it was not until the time of Croesus that their subjugation was completed. When Croesus was conquered (before 546 B.C.) by Cyrus the Great of Persia, the Greek cities came under Persian rule. That rule was not very exacting, but it was despotic in nature, and at the beginning of the 5th cent. B.C. the cities rose in revolt against Darius I. Although the revolt was easily put down, the Persians set out to punish the allies (Athens and Eretria) of the cities. The Persian Wars resulted. Most of the Ionian cities thereby gained a brief freedom, but their fate continued to be subject to treaties with the Persians and changed as Persian fortunes waxed and waned. Alexander the Great easily took (c.335 B.C.) all the Ionian cities in his power, and the Diadochi quarreled over them. The cities continued to be rich and important through the time of the Roman and Byzantine empires. It was only after the Turkish conquest in the 15th cent. A.D. that their culture was destroyed.