4th century BC (400

A century of geopolitical transformation across Eurasia: Macedonian ascendancy and Alexander’s conquests, the start of the Hellenistic era, shifts in Persia, India, China, and early Roman expansion in Italy.

Overview

The 4th century BC spans the years 400 to 301 BC. It was a period of rapid political change and increased long-distance contact across the Mediterranean, Near East and parts of Asia. Established city-state systems and older imperial structures were reshaped by powerful new polities, military innovations and intensified trade and cultural exchange.

Major political developments

Macedon emerged from a peripheral kingdom to dominate mainland Greece under Philip II. His reforms of infantry and tactics allowed Macedon to win decisive influence over the Greek city-states. Philip's son, Alexander the Great, then carried Macedonian power into Asia: he defeated the Achaemenid Persian Empire and campaigned across Anatolia, the Levant, Egypt, Mesopotamia, Iran, Central Asia and into northwestern India, founding cities and transmitting Greek language and institutions.

Key engagements that shaped the era include Chaeronea (338 BC) in Greece and a series of battles in Alexander’s campaign such as the Granicus, Issus and Gaugamela campaigns.
Alexander died in Babylon in 323 BC; his territories fragmented in the Wars of the Diadochi, producing major successor dynasties such as the Ptolemaic kingdom in Egypt and the Seleucid realm in western Asia.

Other regions

The Achaemenid state experienced growing internal pressure before Alexander’s conquests. In India, Alexander’s incursion reached the northwest and was followed by local consolidation that led to the rise of larger states, including the early Maurya polity by the late 4th century BC. In China the Warring States intensified: competing states adopted administrative and military reforms and thinkers debated rival schools such as Confucianism, Daoism and Legalism. In Italy the Roman Republic continued territorial expansion, extending influence over neighboring peoples and setting the stage for later dominance.

Culture, science and legacy

The century saw significant intellectual activity: Plato and his Academy remained influential, and Aristotle produced works that shaped later philosophy and science while serving as tutor to Alexander. Greek literary and artistic forms evolved into a more cosmopolitan Hellenistic style as Greek language and institutions met local traditions across Asia and Egypt. Scientific and technical inquiry advanced in areas such as astronomy, medicine and engineering, often through practical needs of urban life and military technology.

Economy, trade and society

Increased mobility of armies, merchants and artisans promoted wider trade networks linking the Mediterranean basin with the Near East and parts of Central and South Asia. Cities founded or refounded in this period became hubs of administration, commerce and cultural exchange. Social structures adapted to imperial administration and mercantile households, and religious practices exhibited notable syncretism as pantheons and cults interacted across regions.

Timeline of selected developments

Early century: aftermath of the Peloponnesian wars and shifting alliances among Greek city-states.
Mid-century: Philip II’s consolidation of Macedon and the subjugation of much of Greece.
334–323 BC: Alexander’s Asian campaigns and the swift spread of Hellenic institutions.
Late century: fragmentation of Alexander’s empire, establishment of Hellenistic kingdoms, and political consolidation in India and China.

Notable themes

Transition from competitive city-state systems to large dynastic empires and monarchies.
Military innovation and mobility enabling rapid territorial change.
Widespread cultural and administrative exchange that shaped subsequent Mediterranean and Asian history.

4th century BC (400–301 BC)