Ionia Historic region on the w coast of Asia Minor (Turkey), including the neighbouring Aegean islands. The area was settled by people from Mycenae in Greece in the 11th and 10th centuries bc. Miletus and Ephesus became the most important of the prosperous Ionian cities. Ionia was conquered by the Persians in the 6th century bc, then fell under Athenian domination until the Persians regained control in the 4th century bc. After the conquests of Alexander the Great, Ionia was ruled by Hellenistic kings and from the 2nd century bc was part of the Roman Empire.

Ionia in classical times, the central part of the west coast of Asia Minor, which had long been inhabited by Hellenic people (the Ionians) and was again colonized by Greeks from the mainland from about the 8th century bc.