Overview
This period covers Macedonian rule in Iran, from Alexander’s conquest in 330 BC to the rise of Parthia around 247 BC; the Seleucid state itself survived longer in Syria. After Alexander’s death in 323 BC, his general Seleucus I Nicator won the eastern satrapies, and by c. 305 BC he ruled as king from Babylonia and Mesopotamia to the Indus; Syria followed after the battle of Ipsus (301 BC) and Asia Minor after Corupedium (281 BC).
Key developments
Greek and Macedonian colonists settled across the empire, and new Greek-style cities were founded: Seleucia on the Tigris served as an eastern capital, while Ai-Khanoum in the far east shows Greek city life deep in Asia. Greek was used in administration alongside Aramaic. Cultural exchange ran both ways — Babylonian astronomy, Iranian administrative tradition, and eastern cults entered the Greek world. In a famous bargain of c. 303 BC, Seleucus traded the Indus provinces to the Mauryan emperor Chandragupta for 500 war elephants.
End and transition
Seleucid control of the Iranian plateau was always loose, and in the mid-3rd century BC the eastern provinces slipped away: Bactria’s Greek governor declared independence, and around 247 BC the Parni chief Arsaces seized Parthia — the conventional start of the Parthian era. The Seleucids still held western Iran and Mesopotamia until the Parthian king Mithridates I took Media and Seleucia in the 140s BC.