It would require almost four decades after Alexander's death for a new state system to emerge in the Near and Middle East. During those four decades the hope of maintaining intact Alexander's empire proved to be a seductive will-o'-the-wisp. Efforts to hold the empire together were frustrated by alliances of Alexander's surviving generals. First Perdiccas, whom Alexander had designated to administer the empire after his death, tried to maintain the empire intact in his capacity as regent for Alexander's mentally retarded half-brother, Philip III (323-316 B.C.) and his infant son Alexander IV (316-312 B.C.). After Perdiccas's death in 321 B.C., Antigonus the One Eyed (306-301 B.C.), Alexander's Satrap (i.e., governor) of Phrygia, also attempted to defend the unity of the empire. Both, however, failed. The result was that by the end of the wars of Alexander's successors in 280 B.C., his empire had broken up into three major kingdoms ruled by Macedonian dynasties: the Ptolemies, whose realm included Egypt, Palestine, Libya, and Cyprus; the Seleucids, whose territories extended from the Mediterranean to the borders of India; and the Antigonids, in Macedon and northern Greece.
The kingdoms that constituted the Hellenistic political world had hardly come into existence when their survival was threatened by severe internal and external stresses. Particularly hard hit were the Seleucid and Ptolemaic kingdoms. The former, centered in Syria but having to guard against threats on fronts as distant as western Turkey and the borders of India, proved especially vulnerable to separatist tendencies. Even before the end of the fourth century B.C., Seleucus I (311-281 B.C.) had ceded his dynasty's claims to Alexander's conquests in India to Chandra Gupta (ca. 324-300 B.C.) , the conqueror of Northern India and founder of the Maurya dynasty. Seleucus I traded his Indian claims for a military alliance and peace on his far eastern frontier. By the mid-third century B.C. the bulk of Seleucid territory in Anatolia had been usurped by a series of small kingdoms of which the most important was that of the Attalids of Pergamum in the northwestern corner of the peninsula. At almost the same time, the migration into central Iran of the Parni (or Parthians), a nomadic people of Iranian stock from Central Asia, temporarily severed communications between the western heart of the Seleucid kingdom and its eastern marches. As a result, a strong Greek-ruled kingdom emerged with its capital at Bactra, modern Balkh, in Afghanistan. One of the Greek rulers of Bactria, Menander (ca. 155-130 B.C.), even conquered much of northern India and under the name Milinda became one of the most revered figures of Buddhism.8 Still, the Syrian and Mesopotamian core of the kingdom remained intact and provided a sufficiently strong base for Antiochus III (223-187 B.C.), a Seleucid, to launch a counteroffensive at the end of the third century B.C. that restored his dynasty's authority over most of its former territory.
The Ptolemies faced less severe problems in their Egyptian fortress, but even so, a combination of native revolts, military defeats by the Seleucids, and crises over the succession to the throne brought the kingdom to the verge of dissolution late in the third century B.C. The threatened collapse was averted, however, by the vigorous action of Ptolemy V (204-180 B.C.) in the early second century B.C., and the dynasty managed to retain its hold on its Egyptian heartland until the end of the Hellenistic period. Thus, for the better part of two centuries the political life of western Asia and the eastern Mediterranean took place within the framework provided by the three major Macedonian kingdoms. It was the advance of Rome in the west and Parthia in the east that finally put an end to the world created by Alexander's conquests.