The Achaemenid Empire, also called the First Persian Empire, was an ancient Iranian empire based in Western Asia founded by Cyrus the Great. Ranging from the Balkans and Eastern Europe proper in the west to the Indus Valley in the east, it was larger than any previous empire in history, spanning 5.5m km2. Incorporating various peoples of different origins and faiths, it is notable for its successful model of a centralised, bureaucratic administration, 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 army.