The Persian Wars The Persian Wars were a 20-year conflict that lasted from 490 B.C. to 479 B.C., in which the kings of the Persian Empire made an effort to acquire Greece. The independent city-states banned together and successfully resisted these attacks. The Greek colonies in Asia Minor were conquered, in 550 B.C., by Croesus, King of Lydia, and brought into the Lydian Empire. Croesus was a mild ruler and an ally of Sparta. In 546 B.C., Croesus was overthrown by Cyrus the Great, king of Persia. Except for the island of Samos, which defended itself, the Greek city-states in Asia and the coastal islands then became part of the Persian Empire.