text: The Achaemenid Empire, also called the First Persian Empire, was an empire based in Western Asia, founded by Cyrus the Great. Ranging at its greatest extent from the Balkans and Eastern Europe proper in the west to the Indus Valley in the east, it was one of the largest empires in history, spanning 5.5 million square kilometers, and was larger than any previous empire in history. It is equally notable for its successful model of a centralised, bureaucratic administration (through satraps under the King of Kings), for building infrastructure such as road systems and a postal system, the use of an official language across its territories, and the development of civil services and a large professional army. The empire's successes inspired similar systems in later empires. It is noted in Western history as the antagonist of the Greek city-states during the Greco-Persian Wars and for the emancipation of the Jewish exiles in Babylon. 
  
  By the 7th century BC, the Persians had settled in the southwestern portion of the Iranian Plateau in the region of Persis, which came to be their . From this region, Cyrus the Great advanced to defeat the Medes, Lydia, and the Neo-Babylonian Empire, establishing the Achaemenid Empire. Alexander the Great, an avid admirer of Cyrus the Great, conquered most of the empire by 330 BC. Upon his death, most of the empire's former territory came under the rule of the Ptolemaic Kingdom and Seleucid Empire, in addition to other minor territories which gained independence at that time. The Iranian population of the central plateau reclaimed power by the second century BC under the Parthian Empire.