Alexander died in Babylon in June 323 BCE, aged only 32, probably from a febrile illness. Asked who should succeed him, he is said to have answered 'the strongest' — a phrase, true or invented, that summed up the next four decades. His marshals — Antigonus, Seleucus, Ptolemy, Lysimachus, Cassander — first shared a regency and then turned on one another. The Battle of Ipsus in 301 BCE drew the lasting map: the Ptolemies in Egypt, the Seleucids across a vast belt from Syria to Iran, the Antigonids in Macedon, and later the Attalids at Pergamon.

The world that emerged was of a new kind: regional dynasties ruled by a Greek minority while local populations — Egyptians, Persians, Babylonians, Jews, Bactrians — kept their own institutions. Rulers presented themselves at once as pharaohs, kings, and gods. Greek simplified into a single 'koine' dialect and became a common medium of communication from one end of this world to the other — centuries later, the language of the New Testament.

Cultural weight shifted from the old city-states to new metropoles. At Alexandria the Ptolemies founded the greatest library of the ancient world and the Mouseion, a research institution where Euclid systematised geometry, Eratosthenes measured the Earth's circumference, and Aristarchus proposed a heliocentric model. Pergamon rose as a rival with its own library and great altar. Antioch became the crossroads of the eastern Mediterranean. Art moved beyond the idealised calm of the Classical period; Hellenistic sculpture openly showed emotion, age, and pain — the Laocoön, the Dying Gaul, the Winged Victory of Samothrace.

The Hellenistic age formally ends in 30 BCE with Cleopatra's death and the absorption of Egypt by Rome. But the hellenised eastern Mediterranean survived as the cultural skeleton of both the Roman Empire and Byzantium; the spread of early Christianity travelled along the routes Greek had already paved.