How did Alexander the Great end Achaemenid rule in Iran?

Alexander the Great ended Achaemenid rule in Iran through a series of decisive military victories and the systematic occupation of the empire's key administrative centers. Following his initial successes in Asia Minor and his victory at the Battle of Issus in 333 BCE, Alexander moved to isolate the Persian fleet by conquering the Mediterranean coast and Egypt.12

The decisive turning point occurred on October 1, 331 BCE, at the Battle of Gaugamela, where Alexander’s forces defeated the army of Darius III. This victory effectively shattered the Achaemenid military power. Alexander subsequently occupied the major capitals of Babylon, Susa, and Persepolis.132

The symbolic end of the Achaemenid order was marked by the burning of the royal palace at Persepolis in 330 BCE. Darius III, having fled into the eastern provinces, was eventually deposed and murdered by his own satrap, Bessus, in 330 BCE, which finalized the collapse of the Achaemenid Empire.4215