550-331 BC Persian Empire

The Achaemenids were a dynasty from south-central Iran who created the largest empire the world had seen. Also known today as the Persian Empire, it extended from Bulgaria and Libya to north India and Central Asia. Its formation began with Cyrus II (reigned 559-530 BC) who conquered Media (central Iran and eastern Anatolia), Lydia (western Anatolia) and Babylonia (Mesopotamia and the Levant). His son Cambyses (reigned 530-522 BC) conquered Egypt in 525 BC. A crisis followed the death of Cambyses and Darius I emerged as king (522-486 BC). The empire was stabilised and a system of regional governors (satraps) was established.

Darius and later his son Xerxes (reigned 486-465 BC) attempted to force the mainland Greeks to acknowledge Persian power but Sparta and Athens refused to yield. Defeats at Marathon in 490 BC and at Salamis in 480 BC brought an end to Achaemenid expansion. A succession of weak leaders led to political intrigue and rebellions in the satrapies. The last Achaemenid ruler, Darius III (reigned 336-330), was defeated by Alexander III of Macedon (Alexander the Great) at the battle of Gaugamela in 331 BC. Darius was murdered by one of his own generals from the satrapy of Bactria who tried to take the title of king of Persia but was himself murdered, and Alexander claimed the empire.