The Greco-Persian Wars (also often called the Persian Wars) were a series of conflicts between the Achaemenid Empire and Greek city-states that started in 499 BC and lasted until 449 BC. The collision between the fractious political world of the Greeks and the enormous empire of the Persians began when Cyrus the Great conquered the Greek-inhabited region of Ionia in 547 BC. Struggling to control the independent-minded cities of Ionia, the Persians appointed tyrants to rule each of them. This would prove to be the source of much trouble for the Greeks and Persians alike.