The Persian Empire was a series of successive Iranian or Iraniate empires that ruled over the Iranian plateau, the original Persian homeland, and beyond in Western Asia, South Asia, Central Asia and the Caucasus. The first Persian Empire formed under the Median Empire (728 BC-559 BC) after defeating and ending the Assyrian Empire with the help of Babylonians.

Achaemenid Persian Empire (550–330 BC) was the largest empire of the ancient world and the most widespread entity of it was under Darius the Great(Persian:داریوش کبیر) and Xerxes the Great(Persian:خشایارشا or خشایارشاه) — famous in antiquity as the foe of the classical Greek states (See Greco-Persian Wars) — a united Persian kingdom that originated in the region now known as Pars province (Fars province) of Iran.

It was formed under Cyrus the Great, who took over the empire of the Medes, and conquered much of the Middle East, including the territories of the Babylonians, Assyrians, the Phoenicians, and the Lydians. Cambyses, Son of Cyrus the Great, continued his conquests by conquering Egypt. The Achaemenid Persian Empire was ended during the Wars of Alexander the Great, but Persian Empire arose again under the Parthian and Sassanid Empires of Iran, followed by Iranian post-Islamic Empires like Safavids, up to the modern day Iran.

Most of the successive states in Greater Iran prior to March 1935 are collectively called the Persian Empire by Western historians.

Virtually all the successor empires of Persia were major regional and some major international powers in their day.

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