Ionia, known in Old Persian as Yauna, was a region within the satrapy of Sardis within the First Persian Empire. The first mention of the Yauna is at the Behistun inscription. The Ionians were conquered by Cyrus the Great and according to Herodotus, they were placed in the same tax district (the first) as the Pamphylians, Lycians, Magnesians, Aeolians, Milyans, and Carians. It is unclear to what extent the Yauna were advantaged or disadvantaged by Persian rule, and what caused the Ionian Revolt which broke out in c.499 BC and lasted until 494 BC. The main source, Herodotus, puts it down to the personal ambitions of two men of Miletus, Histiaeus and Aristagoras; modern scholars debate what the underlying reasons may have been; arguments for economic and political causes are variously put forward, but there are no clear sources which can give a definitive answer.
After the revolt was put down, the Ionian cities were subdued by some pragmatic and enlightened measures by the Persian satrap of Sardis, Artaphrenes. The Ionians are reported to have served with the Persian forces which were defeated at Marathon by the Athenians and Plataeans in 490, while they also fought on the Persian side during Xerxes' great invasion of 480-479. It was only after the Persians were defeated at Plataea in 479 that the Ionian cities had the confidence to revolt again, defeating the Persian forces at Cape Mycale in the same year. Soon afterwards, they signed up to a common defence league led by Athens, known today as the Delian League. However, these cities soon came under the domination of Athens. After the Peloponnesian War and the destruction of Athenian power, Sparta ceded them back to Persia in the peace of Antalcidas. Ionia remained under Persian rule until the campaigns of Alexander the Great.
Beside to Yaunas of the plain and sea, there are also mentioned Yauna paradraya (Ionians beyond or across the sea such as Naxos, Thasos and Byzantium) as well the Yauna takabara (Ionians with sunhats, the Macedonians) in Skudra satrapy.
- The Persian Empire: Studies in Geography and Ethnography of the Ancient Near East, 1968, p. 345, Ernst Herzfeld, Gerold Walser