The Achaemenid Persian empire was the largest that the ancient world had seen, extending from Anatolia and Egypt across western Asia to northern India and Central Asia. Its formation began in 550 B.C., when King Astyages of Media, who dominated much of Iran and eastern Anatolia (Turkey), was defeated by his southern neighbor Cyrus II (“the Great”), king of Persia (r. 559–530 B.C.). This upset the balance of power in the Near East. The Lydians of western Anatolia under King Croesus took advantage of the fall of Media to push east and clashed with Persian forces. The Lydian army withdrew for the winter but the Persians advanced to the Lydian capital at Sardis, which fell after a two-week siege. The Lydians had been allied with the Babylonians and Egyptians and Cyrus now had to confront these major powers. The Babylonian empire controlled Mesopotamia and the eastern Mediterranean. In 539 B.C., Persian forces defeated the Babylonian army at the site of Opis, east of the Tigris. Cyrus entered Babylon and presented himself as a traditional Mesopotamian monarch, restoring temples and releasing political prisoners. The one western power that remained unconquered in Cyrus’ lightning campaigns was Egypt. It was left to his son Cambyses to rout the Egyptian forces in the eastern Nile Delta in 525 B.C. After a ten-day siege, Egypt’s ancient capital Memphis fell to the Persians.
A crisis at court forced Cambyses to return to Persia but he died en route and Darius I (“the Great”) emerged as king (r. 522–486 B.C.), claiming in his inscriptions that a certain “Achaemenes” was his ancestor. Under Darius the empire was stabilized, with roads for communication and a system of governors (satraps) established. He added northwestern India to the Achaemenid realm and initiated two major building projects: the construction of royal buildings at Susa and the creation of the new dynastic center of Persepolis, the buildings of which were decorated by Darius and his successors with stone reliefs and carvings. These show tributaries from different parts of the empire processing toward the enthroned king or conveying the king’s throne. The impression is of a harmonious empire supported by its numerous peoples. Darius also consolidated Persia’s western conquests in the Aegean. However, in 498 B.C., the eastern Greek Ionian cities, supported in part by Athens, revolted. It took the Persians four years to crush the rebellion, although an attack against mainland Greece was repulsed at Marathon in 490 B.C.
Darius’ son Xerxes (r. 486–465 B.C.) attempted to force the mainland Greeks to acknowledge Persian power, but Sparta and Athens refused to give way. Xerxes led his sea and land forces against Greece in 480 B.C., defeating the Spartans at the battle of Thermopylae and sacking Athens. However, the Greeks won a victory against the Persian navy in the straits of Salamis in 479 B.C. It is possible that at this point a serious revolt broke out in the strategically crucial province of Babylonia. Xerxes quickly left Greece and successfully crushed the Babylonian rebellion. However, the Persian army he left behind was defeated by the Greeks at the Battle of Plataea in 479 B.C.
Much of our evidence for Persian history is dependent on contemporary Greek sources and later classical writers, whose main focus is the relations between Persia and the Greek states, as well as tales of Persian court intrigues, moral decadence, and unrestrained luxury. From these we learn that Xerxes was assassinated and was succeeded by one of his sons, who took the name Artaxerxes I (r. 465–424 B.C). During his reign, revolts in Egypt were crushed and garrisons established in the Levant. The empire remained largely intact under Darius II (r. 423–405 B.C), but Egypt claimed independence during the reign of Artaxerxes II (r. 405–359 B.C). Although Artaxerxes II had the longest reign of all the Persian kings, we know very little about him. Writing in the early second century A.D., Plutarch describes him as a sympathetic ruler and courageous warrior. With his successor, Artaxerxes III (r. 358–338 B.C), Egypt was reconquered, but the king was assassinated and his son was crowned as Artaxerxes IV (r. 338–336 B.C.). He, too, was murdered and replaced by Darius III (r. 336–330 B.C.), a second cousin, who faced the armies of Alexander III of Macedon (“the Great”). Ultimately Darius III was murdered by one of his own generals, and Alexander claimed the Persian empire. However, the fact that Alexander had to fight every inch of the way, taking every province by force, demonstrates the extraordinary solidarity of the Persian empire and that, despite the repeated court intrigues, it was certainly not in a state of decay.