Which factors led to the decline of the persian empire

After the death of Darius, his son Xerxes ruled until 465 B.C. Xerxes was a cruel but weak king who was also defeated by the Greeks in the Persian Wars. During Xerxes’ reign, the Persian Empire declined. Although the empire continued for more than a century, it grew weaker as it constantly faced conspiracies, assassinations, and revolts by the people who were burdened with heavy taxes. Alexander the Great defeated King Darius III and the Persian army in 330 B.C. Darius was subsequently assassinated by one of his own followers. Although Alexander retained the Persian system of government until his own death in 323 B.C. Darius’s defeat marked the end of the Achaemenid dynasty and the Persian Empire.