General Notes

Khosrow I, byname KHOSROW ANUSHIRVAN (Persian: "Khosrow of the Immortal Soul"), or KHOSROW THE JUST (d. AD 579), Persian king who ruled the Sasanian empire from 531 to 579 and was remembered as a great reformer and patron of the arts and scholarship.
Rise to power.
Little is known of the early life of Khosrow beyond legends. One story says that when Khosrow's father, King Kavadh, took refuge with the Hephthalites, eastern neighbours of Iran, on the way (near the town of Nishapur) he married a peasant's daughter, who gave birth to Khosrow. At his father's death Khosrow did not at first succeed him, but in a struggle for the throne he was successful and put to death his brothers. At the end of his father's reign, great social disorders had occurred because of a religious revolution of a sect called the Mazdakites. Khosrow first restored order and then launched reforms to transform the declining Sasanian empire.
Reforms.
The reform of taxation was the most important of his actions, and it was probably copied from the Roman system inaugurated by the emperor Diocletian. Previously in the Sasanian empire taxes had been levied on the yield of land; Khosrow established a fixed sum rather than a yearly variation. Other taxes were introduced that brought stability to the income of the state and were also fairer to those who paid the taxes. Khosrow's program of taxes lasted into Islamic times.
Khosrow also reorganized the Sasanian bureaucracy, and the system of ministries, or divans, under a prime minister is said to have been initiated by him. He was fortunate during most of his reign in having a capable prime minister called Bozorgmehr, who became famous in story and legend for his wisdom and abilities.
Under Khosrow the process of decentralization of the power of the monarch was reversed, and the lower aristocracy, or knights, called dihqans, grew in importance at the expense of the great feudal lords, who had been more powerful under Khosrow's predecessors. It is difficult to know how many changes really can be attributed to Khosrow's reign and how many are arbitrarily assigned to him because of his place in history. Whether the religiously sanctioned division of society into priests, warriors, bureaucracy, and common folk was codified under his reign, as claimed by some sources, is difficult to determine.
Military campaigns.
Khosrow also reorganized the army and appointed four chief commanders to guard the four frontiers of Iran. On the frontier against the Byzantines and their Arab allies in the Syrian Desert, against the peoples of the steppes of southern Russia at the town of Derbent between the Caucasus Mountains and the Caspian Sea, and to the east of the sea in the present Turkmen steppes, Khosrow built defensive walls. The army, however, did not remain on the defensive, for Khosrow's reign is noted for his wars against the Byzantines. In 540 Antioch was conquered and held for a short time by Khosrow. He brought many prisoners from Antioch and settled them in a new town near his capital of Ctesiphon, modeled on old Antioch. In the east, Khosrow, in alliance with the Turks, a new power in Central Asia, crushed the Hephthalites, and he established a hegemony over many of their principalities. The Sasanian frontier in the east reached the Amu Darya (Oxus River) during his reign.
He also fought extensively in Armenia and Lazica in the Caucasus. Furthermore, under his reign a Sasanian army conquered Yemen. Khosrow relied on a professional army more than his predecessors, who had summoned feudal levies when they set out to war.
Patron of culture.
Khosrow was also a great patron of culture, and in 529, when the ancient academy of Athens was closed, a number of Greek philosophers migrated to the Sasanian empire, where they were well received by the ruler. The later famous medical school of Gondeshapur was probably started in Khosrow's reign, and the famous physician Burzoe is supposed to have been sent to India by Khosrow to gather Sanskrit books of learning to be translated into the Middle Persian language. The game of chess reportedly was also brought by him from India. Astronomy and astrology flourished at the court of Khosrow, and one star table (called the zij-i Shahriyar), which was the basis of many later Islamic tables, is said to have originated during the reign of Khosrow. Several works of Middle Persian, such as the Book of Deeds of Ardashir (Karnamak), are attributed to this period. Likewise, some scholars claim that the codification of the Avesta, the sacred book of the Zoroastrian religion, as well as the creation of a special Avestan alphabet to record the text, took place at the order of Khosrow. Further, it is supposed that the stories and legends of ancient Iran were gathered into a Khwatay-namak ("Book of Kings") in the time of Khosrow and thus provided the source for Ferdowsi's immortal epic much later. Some of the names found in Ferdowsi's Shah-nameh appear among the royal family of Khosrow, which indicates at the least an interest on the part of the monarch in ancient legends.
Perhaps more than fact, the stories told about Khosrow have made his name famous in history. Almost any pre-Islamic structure in Iran whose origin is unknown will be attributed to Khosrow by the simple folk. Undoubtedly he built many bridges, roads, and palaces, but much more is assigned to him in legend. The famous palace with the huge arch, called Taq Kisra, in Ctesiphon, near modern Baghdad, is said to date from Khosrow I, but this is uncertain. Several collections of wise sayings of this monarch, as well as stories about him, have been preserved in Arabic or New Persian versions. In them his reputation for justice as well as wisdom is constantly cited. The splendour of the court and the glory of his reign provided models for the later 'Abbasid court in Baghdad, and many of the institutions established by Khosrow were maintained in Islamic times, when Khosrow was hailed as the model pre-Islamic ruler to be emulated by Muslim princes. [Encyclopaedia Britannica CD '97, CHOSROES I]
Chosroes I., "the blessed" (Anushirvan), A.D. 531-579, successor of Kavadh I., and the most famous of the Sassanid kings. At the beginning of his reign he concluded an "eternal" peace with the emperor Justinian, who wanted to be free for the conquest of Africa and Sicily. But successes against the Vandals and Goths caused Chosroes to renew the war in 540. He invaded Syria and took Antioch, and during the next years fought successfully in Lazica or Lazistan (the ancient Colchis), on the Black sea, and in Mesopotamia. In 545 an armistice was concluded and in 562 a peace for 50 years in which the Persians left Lazistan to the Romans, and the Romans paid subsidies to Persia. Meanwhile in the east the Hephthalites had been attacked by the Turks, who now appear for the first time in history. Chosroes united with them and conquered Bactria, while he left the country north of the Oxus to the Turks. He also assisted the dynasts of Yemen to expel the Ethiopians and Yemen became dependent on Persia. In 571 a new war with Rome broke out about Armenia, in which Chosroes conquered the fortress Dara on the Euphrates, invaded Syria and Cappadocia, and returned with large booty. During the negotiations with the emperor Tiberius, Chosroes died in 579, and was succeeded by his son Hormizd IV.
Although Chosroes had extirpated the heretical Persian sect of the Mazdakites he was a tolerant adherent of Zoroastrian orthodoxy. He introduced a system of taxation based upon a survey of landed possessions begun by his father. [Encyclopaedia Britannica, 1961ed., Vol. 5, p. 524B, KHOSROW I]