Ionia, in ancient geography, was the name given to a portion of the western coast of Asia Minor, adjoining the Aegean Sea and bounded on the east by Lydia. It consisted of a narrow strip of land near the coast, which together with the adjacent islands was occupied by immigrant Greeks of the Ionic race, and thus distinguished from the interior district, inhabited by the Lydians.
According to the universal Greek tradition, the cities of Ionia were founded by emigrants from the other side of the Aegean and their settlement was connected with the legendary history of the Ionic race in Attica, by the statement that the colonists were led by Neleus and Androclus, sons of Codrus, the last king of Athens. In accordance with this view the "Ionic migration," as it was called by later chronologers, was dated by them one hundred and forty years after the Trojan war, or sixty years after the return of the Heraclidae into the Peloponnese. Without assigning any definite date, we may say that recent research (1910) has tended to support the popular Greek idea that Ionia received its main Greek element rather late--after the descent of the Dorians, and, therefore, after any part of the Aegean period. The only Aegean objects yet found (1910) in or near Ionia are some sherds of the very latest Minoan age at Miletus. It is not probable that all the Greek colonists were of the not numerous Ionian race. Herodotus tells us that they comprised settlers from many different tribes and cities of Greece (a fact indicated also by the local traditions of the cities), and that they intermarried with the native races.
The cities called Ionian in historical times were twelve in number, an arrangement copied as it was supposed from the constitution of the Ionian cities in Greece which had originally occupied the territory in the north of the Peloponnese subsequently held by the Achaeans. These were (from south to north) Miletus, Myus, Priene, Ephesus, Colophon, Lebedus, Teos, Erythrae, Clazomenae and Phocaea, together with Samos and Chios. Smyrna, originally an Aeolic colony, was afterwards occupied by Ionians from Colophon, and became an Ionian city--an event which had taken place before the time of Herodotus. But at what period it was admitted as a member of the league we have no information. The cities above enumerated unquestionably formed a kind of league, of which participation in the Pan-Ionic festival was the distinguishing characteristic. This festival took place on the north slope of Mt. Mycale in a shrine called the Panionium. But like the Amphictyonic league in Greece, the Ionic was rather of a sacred than a political character; every city enjoyed absolute autonomy, and, though common interests often united them for a common political object, they never formed a real confederacy like that of the Achaeans or Boeotians. The advice of Thales of Miletus to combine in a political union was rejected.
Ionia was of small extent, not exceeding 90 geographical miles in length from north to south, with a breadth varying from 20 to 30 miles, but to this must be added the peninsula of Mimas, together with the two large islands. So intricate is the coastline that the voyage along its shores was estimated at nearly four times the direct distance. A great part of this area was, moreover, occupied by mountains. Of these the most lofty and striking were Mimas and Corycus, in the peninsula which stands out to the west, facing the island of Chios; Sipylus, to the north of Smyrna; Corax, extending to the south-west from the Gulf of Smyrna, and descending to the sea between Lebedus and Teos; and the strongly marked range of Mycale, a continuation of Messogis in the interior, which forms the bold headland of Trogilium or Mycale, opposite Samos. None of these mountains attains a height of more than 4000 feet The district comprised three extremely fertile valleys formed by the outflow of three rivers, among the most considerable in Asia Minor: the Hermus in the north, flowing into the Gulf of Smyrna, though at some distance from the city of that name; the Caster, which flowed under the walls of Ephesus; and the Maeander, which in ancient times discharged its waters into the deep gulf that once bathed the walls of Miletus, but whith has been gradually filled up by this river's deposits. With the advantage of a peculiarly fine climate, for which this part of Asia Minor has been famous in all ages, Ionia enjoyed the reputation in ancient times of being the most fertile of all the rich provinces of Asia Minor; and even in modern times, though very imperfectly cultivated, it produces abundance of fruit of all kinds, and the raisins and figs of Smyrna supply almost all the markets of Europe.
The colonies naturally became prosperous. Miletus especially was at an early period one of the most important commercial cities of Greece; and in its turn became the parent of numerous other colonies, which extended all around the shores of the Euxine Sea and the Propontis from Abydus and Cyzicus to Trapezus and Panticapaeum. Phocaea was one of the first Greek cities whose mariners explored the shores of the western Mediterranean. Ephesus, though it did not send out any colonies of importance, from an early period became a flourishing city and attained to a position corresponding in some measure to that of Smyrna at the present day.
The first event in the history of Ionia of which we have any trustworthy account is the inroad of the Cimmerii (who ravaged a great part of Asia Minor, including Lydia, and sacked Magnesia on the Maeander, but were foiled in their attack upon Ephesus. This event may be referred to the middle of the 7th century BC. About 700 BC Gyges, first Mermnad king of Lydia, invaded the territories of Smyrna and Miletus, and is said to have taken Colophon as his son Ardys did Priene. But it was not till the reign of Croesus (560 - 545 BC) that the cities of Ionia successively fell under Lydian rule. The defeat of Croesus by Cyrus was followed by the conquest of all the Ionian cities. These became subject to the Persian monarchy with the other Greek cities of Asia. In this position they enjoyed a considerable amount of autonomy, but were for the most part subject to local despots, most of whom were creatures of the Persian king. It was at the instigation of one of these despots, Histiaeus of Miletus, that in about 500 BC the principal cities ignited the Ionic Revolt against Persia. They were at first assisted by the Athenians, with whose aid they penetrated into the interior and burnt Sardis, an event which ultimately led to the Persian invasion of Greece. But the fleet of the Ionians was defeated off the island of Lade, and the destruction of Miletus after a protracted siege was followed by the reconquest of all the Asiatic Greeks, insular as well as continental.
The victories of the Greeks during the great Persian war had the effect of enfranchizing their kinsmen on the other side of the Aegean; and the battle of Mycale (479 BC), in which the defeat of the Persians was in great measure owing to the Ionians, secured their emancipation. They henceforth became the dependent allies of Athens (see Delian League), though still retaining their autonomy, which they preserved until the peace of Antalcidas in 387 BC once more placed them as well as the other Greek cities in Asia under the nominal dominion of Persia. They appear, however, to have retained a considerable amount of freedom until the invasion of Asia Minor by Alexander the Great. After the battle of the Granicus most of the Ionian cities submitted to the conqueror. Miletus, which alone held out, was reduced after a long siege (334 BC). From this time they passed under the dominion of the successive Macedonian rulers of Asia, but continued, with the exception of Miletus, to enjoy great prosperity both under these Greek dynasties and after they became part of the Roman province of Asia.
Ionia has laid the world under its debt not only by giving birth to a long roll of distinguished men of letters and science (see Ionian School of Philosophy), but by originating the distinct school of art which prepared the way for the brilliant artistic development of Athens in the 5th century. This school flourished in the 8th, 7th and 6th centuries, and is distinguished by the fineness of workmanship and minuteness of detail with which it treated subjects, inspired always to some extent by non-Greek models. Naturalism is progressively obvious in its treatment, e.g. of the human figure, but to the end it is still subservient to convention. It has been thought that the Ionian migration from Greece carried with it some part of a population which retained the artistic traditions of the "Mycenaean" civilization, and so caused the birth of the Ionic school; but whether this was so or not, it is certain that from the 8th century onwards we find the true spirit of Hellenic art, stimulated by commercial intercourse with eastern civilizations, working out its development chiefly in Ionia and its neighbouring isles. The great names of this school are Theodorus and Rhoecus of Samos; Bathycles of Magnesia on the Maeander; Glaucus, Melas, Micciades, Archermus, Bupalus and Athenis of Chios. Notable works of the school still extant are the famous archaic female statues found on the Athenian Acropolis in 1885-1887, the seated statues of Branchidae, the Nike of Archermus found at Delos, and the objects in ivory and electrum found by D G Hogarth in the lower strata of the Artemision at Ephesus.