Cyaxares of Media - Ahasuerus of the Bible, Book of Daniel - had unified his tribes and allied them with Babylonia to take Nineveh and destroy Assyria. He furthered his realm by investing Urartu and pushing towards Lydia. His son Astyages - the biblical Darius the Mede of the Book of Daniel - allied his land with the Persians by marrying his only daughter to Cambyses, the King of Anzan (Persia). Their son Cyrus, heir of the thrones of Persia and Media, was destined to become the founder of the Empire.
How this came about is not quite clear. It is sure that Astyages had introduced Babylonian and Assyrian court ceremonial, with its worship of the god-like king, into Media, which was repugnant to his tribes. Cyrus renounced his vassalage and stopped paying tribute. The Median army was defeated close to Parsagad (Pasargadae) when much of it defected to Cyrus, and the Persians and Medes were united (533 B.C.). Cyrus accepted his Median grandfather as senior advisor, incorporating his Medes as equal partners into the empire and then negotiated the federation of Elam and Urartu as first satrapies, setting the peculiar pattern of the “federal” Empire which followed. The Medes and Persians comprised the nobility and ruling caste and did not have to pay taxes, in return for which exemption they formed and recruited the bulk of the army.
Croesus, King of Lydia, used the news of the civil war in Iran to attack the Median border provinces. Cyrus responded by leading his army through northern Mesopotamia. A battle was joined at the Cilician Gates, which after heavy losses on both sides ended with a draw. Cyrus feinted withdrawal, Crocuses returned to Sardis and disbanded his army, since winter had set in and snow could be expected at any moment. Cyrus waited for several weeks and then marched his army in forced marches to Sardis, to surprise Croesus completely. Herodotus reports that Cyrus’ progress was so swift that he “arrived his own messenger”. The Lydian cavalry rallied and attacked with desperate force only to be foiled by another Cyrus stratagem. Knowing that horses shied away from camels and that no infantry levies were available to Croesus at the time, he put his camel troops into the first line of battle. He thus invested all of Lydia (547) and secured Asia Minor as well as the strategically important area north of Syria. Unlike his Mesopotamian predecessors, who executed the conquered kings, Cyrus incorporated the old rulers into his government and the humbled Croesus, whose egotism and wealth are a favorite subject of Greek legend, became a major advisor. From King of the Persians, king of Anzan, Cyrus had become King of Kings. King of All Lands. The attack on Mesopotamia was mounted, Babylon was taken in 538 and within 14 years after the unification of Persians and Medes the empire encompassed the entire Persian highland, Mesopotamia and Transoxiana in Central Asia.
During his ensuing eastern campaign Cyrus defeated Vistashpa, King of Chorasmia and first convert of the prophet Zoroaster, incorporating his land into the Persian Empire. Cyrus died later in the same campaign in 530 B.C. in battle against the Amazon Queen of the Sogdians in Transoxiana.
The Persians did not come only as conquerors, but as revolutionary innovators. They brought stability and order through the famed Laws of the Medes and Persians, as well as an unheard-of respect for existing religious institutions, which guaranteed freedom of worship and accepted the religions of all peoples. They permitted the Jews to return to Jerusalem and granted them aid funds to reconstruct their temple, or to settle wherever they wanted in the Achaemenian Empire. Large Jewish communities still exist in Iran from that time. (Isfahan and Shiraz are modern cities believed to have grown out of original Jewish settlements). A general tax of 10% was charged which guaranteed security and freedom from military service - a system adopted 1,000 years later by Islam.
In arid areas the Persian method of irrigation - the qanat system - was introduced and large areas of land made fertile. This proved a resounding success in the Egyptian oases, and in westernmost China. Safe roads permitted unrestricted travel and commerce between the Indus River, Transoxiana, Siberia, and the Mediterranean. Trade was facilitated by one monetary unit, the Daric, of equal value and grade in all parts of the empire.
It should therefore not be astonishing that many of the small Greek trading communities in Asia Minor supported Persian rule and believed they had everything to lose by Greek nationalism. There was a strong “Persian” party In Athens The Persian Wars between “civilized” Greece and “barbarian” Persia were started, according to the Greek father of history Herodotus, by the “mischief” of the Athenians, looting Lydian cities under Persian protection, for profit.
The unity of the Persian homeland was strengthened by the development of three capitals. For winter, the reception of foreigners and general business: Susa in Elam. For summer and the archives: Median Hamadan, the Ecbatana of the Bible. For the spring festival and New Year’s celebration: Persepolis - whose very existence was unknown to foreigners. Pasargadae continued to be used for the coronation ceremonies of new kings.
A system of royal governors (satraps) was worked out, nobles who were related to the king by blood, or who had proven their merit. The centrifugal tendencies in such a great empire were combated by an intelligence service of trusted servants of the king, sent to control the administration of the provinces and reporting at least once a year directly to him - probably at the New Year’s festival in Persepolis. The military administration of each province was under an army general, directly responsible to the king rather than to the local satrap. The basic structure of this highly original administration was initiated by Cyrus the Great and perfected by Darius the Great after he had to combat revolutions in almost all satrapies.
Egypt was added to the empire under Cambyses (529-522). A canal was dug between the Nile and the Red Sea, facilitating transport between the Mediterranean and the eastern shore of Africa and India.
The system worked excellently until sloth and maladministration, incapable rulers, continuous blood letting amongst the nobles, neglect and incompetence of military leadership led to its collapse under Alexander’s thrust in 330 B.C.