Towards the middle of the sixth century B.C., and a few years after the death of Nebuchadnezzar (Nabuchodonosor) the Great, King of Babylon (605-562 B.C.), Western Asia was divided into three kingdoms: the Babylonian Empire, Media, and Lydia; and it was only a question of time which of the three would annihilate the other two. Astyages (585-557 B.C.), the successor of Cyaxares (625-585 B.C.), being engaged in an expedition against Babylonia and Mesopotamia, Cyrus, Prince of Anzan, in Elam, profiting by his absence, fomented a rebellion in Media. Astyages, hearing of the revolt, immediately returned, but was defeated and overthrown by Cyrus, who was proclaimed King of Media. Thus, with the overthrow of Astyages and the accession of Cyrus to the throne, the Median Empire passed into the hands of the Persians (550 B.C.). In 549, Cyrus invaded Assyria and Babylonia; in 546 he attacked Croesus of Lydia, defeated him, and annexed Asia Minor to his realm; he then conquered Bactriana and, in 539, marched against Babylon. In 538 Babylon surrendered, Nabonidus fled, the Syro-Phoenician provinces submitted, and Cyrus allowed the Hebrews to return to Palestine. But in 529 he was killed in battle, and was succeeded by Cambyses, the heir apparent, who put his brother Smerdis to death. In 525 Cambyses, aided by a Phoenician fleet, conquered Egypt and advanced against the Sudan, but was compelled to return to Egypt. On his way home, and while in Syria, being informed that Gaumata, a Magian, pretending to be the murdered Smerdis, had seized the throne, Cambyses committed suicide (522) and was succeeded, in 531, by Darius Hystaspes, who, with six other princes, succeeded in overthrowing the usurper Gaumata.

With the accession of Darius, the throne passed to the second line of descendants of Teispes II, and thus the Elamite dynasty came to an end. This was soon followed by a general revolt in all the provinces, including Babylon, where a son of Nabonidus was proclaimed king. Susiana also rose up in arms, and Darius was confronted with the task of reconquering the empire founded by Cyrus. In 519 Babylon was conquered, all the other provinces, including Egypt, were pacified, and the whole empire reorganized and divided into satrapies with fixed administration and taxes. In 515 the Asiatic Greeks began to rebel, but were crushed by Darius. Thence he marched to the Indus and subjugated the country along its banks. In 499 the Ionians revolted, but were defeated and the city of Miletus destroyed (494 B.C.). In 492 Mardonius, one of Darius's generals, set out to reconquer Greece, concentrating all his forces in Cilicia; but the Persians were defeated at Marathon (490 B.C.). In 485 Darius was succeeded by his son, Xerxes I, who immediately set out to reconquer Egypt and Babylon, and renewed the war against Greece. After the indecisive battles of Thermopylæ and Artemisium, he was defeated by Themistocles at Salamis near Athens (480). During the years 479-465, Xerxes met with constant reverses; he gradually lost Attica, Ionia, the Archipelago, and Thrace, and at last was assassinated by Artabanus and Artaxerxes. The latter, becoming king as Artaxerxes I, in 464 quelled revolts in Bactria and Egypt in the year 454. In 449, the Persian fleet and army having been again defeated near Salamis, in Cyrus, a treaty of peace was made between Persia and Athens. Artaxerxes died in 424 and was succeeded by his eldest son, Xerxes II, who reigned but forty-five days and was murdered by his half-brother Sogdianus. Sogdianus reigned six months and was murdered by Nothus, who ascended the throne in 423 as Darius II Nothus (the Bastard).

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