CHOSROES, in Middle and Modern Persian Khosrau ("with a good name"), a very common Persian name, borne by a famous king of the Iranian legend (Kai Khosrau); by a Parthian king, commonly called by the Greeks Osroes (q.v.); and by the following two Sassanid kings.
1. Chosroes I., "the Blessed" (Anushirvan), 531-579, the favourite son and 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 have his hands free for the conquest of Africa and Sicily. But his successes against the Vandals and Goths caused Chosroes to begin the war again in 540. He invaded Syria and carried the inhabitants of Antioch to his residence, where he built for them a new city near Ctesiphon under the name of Khosrau-Antioch or Chosro-Antioch. During the next years he fought successfully in Lazica or Lazistan (the ancient Colchis, q.v.), on the Black Sea, and in Mesopotamia. The Romans, though led by Belisarius, could do little against him. In 545 an armistice was concluded, but in Lazica the war went on till 556. At last, in 562, a peace was concluded for 50 years, in which the Persians left Lazistan to the Romans, and promised not to persecute the Christians, if they did not attempt to make proselytes among the Zarathustrians; on the other hand, the Romans had again to pay 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. Many other rebellious tribes were subjected. About 570 the dynasts of Yemen, who had been subdued by the Ethiopians of Axum, applied to Chosroes for help. He sent a fleet with a small army under Vahriz, who expelled the Ethiopians. From that time till the conquests of Mahomet, Yemen was dependent on Persia, and a Persian governor resided here. 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 in the last years of his father extirpated the heretical and communistic Persian sect of the Mazdakites (see Kavadh) and was a sincere adherent of Zoroastrian orthodoxy, he was not fanatical or prone to persecution. He tolerated every Christian confession. When one of his sons had rebelled about 550 and was taken prisoner, he did not execute him; nor did he punish the Christians who had supported him. He introduced a rational system of taxation, based upon a survey of landed possessions, which his father had begun, and tried in every way to increase the welfare and the revenues of his empire. In Babylonia he built or restored the canals. His army was in discipline decidedly superior to the Romans, and apparently was well paid. He was also interested in literature and philosophical discussions. Under his reign chess was introduced from India, and the famous book of Kalilah and Dimnah was translated. He thus became renowned as a wise prince. When Justinian in 529 closed the university of Athens, the last seat of paganism in the Roman empire, the last seven teachers of Neoplatonism emigrated to Persia. But they soon found out that neither Chosroes nor his state corresponded to the Platonic ideal, and Chosroes, in his treaty with Justinian, stipulated that they should return unmolested.
2. Chosroes II., "the Victorious" (Parvez), son of Hormizd IV., grandson of Chosroes I., 590-628. He was raised to the throne by the magnates who had rebelled against Hormizd IV. in 590, and soon after his father was blinded and killed. But at the same time the general Bahram Chobin had proclaimed himself king, and Chosroes II. was not able to maintain himself. The war with the Romans, which had begun in 571, had not yet come to an end. Chosroes fled to Syria, and persuaded the emperor Maurice (q.v.) to send help. Many leading men and part of the troops acknowledged Chosroes, and in 591 he was brought back to Ctesiphon. Bahram Chobin was beaten and fled to the Turks, among whom he was murdered. Peace with Rome was then concluded. Maurice made no use of his advantage; he merely restored the former frontier and abolished the subsidies which had formerly been paid to the Persians. Chosroes II. was much inferior to his grandfather. He was haughty and cruel, rapacious and given to luxury; he was neither a general nor an administrator. At the beginning of his reign he favoured the Christians; but when in 602 Maurice had been murdered by Phocas, he began war with Rome to avenge his death. His armies plundered Syria and Asia Minor, and in 608 advanced to Chalcedon. In 613 and 614 Damascus and Jerusalem were taken by the general Shahrbaraz, and the Holy Cross was carried away in triumph. Soon after, even Egypt was conquered. The Romans could offer but little resistance, as they were torn by internal dissensions, and pressed by the Avars and Slavs. At last, in 622, the emperor Heraclius (who had succeeded Phocas in 610) was able to take the field. In 624 he advanced into northern Media, where he destroyed the great fire-temple of Gandzak (Gazaca); in 626 he fought in Lazistan (Colchis), while Shahrbaraz advanced to Chalcedon, and tried in vain, united with the Avars, to conquer Constantinople. In 627 Heraclius defeated the Persian army at Nineveh and advanced towards Ctesiphon. Chosroes fled from his favourite residence, Dastagerd (near Bagdad), without offering resistance, and as his despotism and indolence had roused opposition everywhere, his eldest son, Kavadh II., whom he had imprisoned, was set free by some of the leading men and proclaimed king. Four days afterwards, Chosroes was murdered in his palace (February 628). Meanwhile, Heraclius returned in triumph to Constantinople, in 629 the Cross was given back to him and Egypt evacuated, while the Persian empire, from the apparent greatness which it had reached ten years ago, sank into hopeless anarchy.