Ancient Persia - Introduction to Persia and the Persian Empire
The Ancient Persians are more familiar to us than the other empire builders of Mesopotamia or the Ancient Near East, the Sumerians , the Babylonians, and the Assyrians, not only because the Persians were more recent, but because they were amply described by the Greeks. Just as one man, Alexander of Macedon (Alexander the Great, ultimately wore the Persians down quickly (in about three years), so the Persian Empire rose to power quickly under the leadership of Cyrus the Great.
We in the West are accustomed to seeing the Persians as the "them" to a Greek "us." No Athenian-style democracy for the Persians, but an absolute monarchy that denied the individual, common man his say in political life. The most important part of the Persian army was a seemingly fearless elite fighting group of 10,000 known as "The Immortals" because when one was killed another would be promoted to take his place. Since all men were eligible for combat until age 50, manpower was not an obstacle for the Persians, although to insure loyalty, the original members of this fighting machine were Persians or Medes.
Cyrus the Great, a religious man and adherent of Zoroastrianism, first came to power by overcoming his in-laws, the Medes (c. 550 B.C.) -- the conquest made easy by many defectors. Cyrus then made peace with the Medes, and cemented the alliance by creating not just Persian, but Median sub-kings known as satraps to rule the provinces. He then conquered the Lydians, the Greek colonies on the Aegean coast, the Parthians, and Hyrcanians. He set up a fortified border along the Jaxartes River in the Steppes, and in 540 B.C., he conquered the Babylonian Empire. The successors of Cyrus conquered Egypt, Thrace, Macedonia, and spread the Persian Empire east to the Indus River.
~ N.S. Gill