Khosrow II, coin, ad 590–628; in the collection of the American Numismatic Society.Courtesy of the American Numismatic Society
The acquaintance with Greek language and literature maintained by the Arsacid court had begun to decline during the last century of that dynasty. Greek versions nonetheless accompany the Parthian and Middle Persian texts of the inscriptions of Ardashīr I and Shāpūr I, as in the case of the Kaʿbe-ye Zardusht inscription. Later inscriptions, however, are only in Parthian and Middle Persian, as in the case of the inscription of Narses at Paikuli.
Most of the comparatively few remaining examples of literature in Book Pahlavi—a form of Middle Persian somewhat different from that used in the Sāsānian inscriptions—is of late or post-Sāsānian date in its actual form, if not in content. This is partly due to the fact that the transition from an oral to a written literary tradition (both religious and secular compositions) took place in the latter part of the Sāsānian era. A passage in a religious text states that “it is proper to consider the living spoken word more weighty than the written.” It should be added that most Sāsānian literary remains are primarily of religious and historical rather than of literary interest. Just as foreign learning appears in religious works, likewise foreign prose works of entertainment came to Persia, where they were translated; among them, in the time of Khosrow I, were Hellenistic romance literature and Indian books of tales, such as Kalīlag and Dimnag, based on the Indian Pañca-tantra, or the legends of Barlaam and Josaphat (Balauhar and Budasaf). Foreign policy
In foreign policy the issues under the Sāsānian kings remained, as of old, the defense and, when possible, the expansion of the eastern and western frontiers. The successful military campaigns in the eastern areas by Ardashīr I and Shāpūr I, which resulted in the annexation of the western part of the Kushān empire, have already been mentioned. Conflicts with Rome
In the west the old contest for northern Mesopotamia—with the fortified cities of Carrhae, Nisibis, and Edessa—continued. The Sāsānians were all the more eager to regain and retain control of Armenia because there the Arsacid dynasty still survived and turned for protection to Rome, with which, in consequence, new wars continually broke out. In the reign of Bahrām II (276–293), the Roman emperor Carus (282–283) invaded Mesopotamia without meeting opposition and reached Ctesiphon. His sudden death, however, caused the Roman army to withdraw. Bahrām II had been prevented from meeting the Roman challenge by the rebellion of his brother, the kūshānshāh Hormizd, who tried to establish an independent eastern empire. This attempt ended in failure, however, and Bahrām II appointed his younger son, the future Bahrām III, as viceroy of Sakastan (Sīstān). After Bahrām II died, Narses, the youngest son of Shāpūr I, contested the succession of Bahrām III and won the crown. In memory of his victory, Narses erected a tower at Paikuli, in the mountains west of the upper Diyālā River, which was discovered in 1843 by the British Orientalist Sir Henry Rawlinson. Decorated with busts of Narses, the monument has a long inscription in Parthian and Middle Persian that tells the story of the events. In 296 Narses was forced to conclude a peace treaty with the Romans by which Armenia remained under Roman suzerainty and certain areas in northern Mesopotamia were ceded to Rome. By this treaty, which lasted for 40 years, the Sāsānians withdrew completely from the disputed districts. The Roman Empire had meanwhile become Christian, and the Syro-Christian populations of Mesopotamia and Babylonia began to feel sympathy with Roman policies for religious reasons. Christianity also became predominant in Armenia after its king adopted the Christian faith in 294. The Sāsānian emperors consequently felt the need to consolidate their Zoroastrianism, and efforts were made to perfect and enforce state orthodoxy. All heresy was proscribed by the state, defection from the official faith was made a capital crime, and persecution of the heterodox, the Christians in particular, began. Competition between Iran and Rome-Byzantium thus took on a religious dimension.
A new war was inevitable. It was begun by Shāpūr II in 337, the year of the death of Constantine I. Shāpūr besieged the fortress city of Nisibis three times without success. The emperor Constantius II (reigned 337–361) conducted the war weakly, but Shāpūr was distracted by the appearance of a new enemy, the nomadic Chionites, on his eastern frontier. After a long campaign against them (353–358), he returned to Mesopotamia and, with the help of Chionite auxiliaries, captured the city of Amida (modern Diyarbakır, Turkey) on the upper Tigris, an episode vividly narrated by the Roman historian Ammianus Marcellinus (c. 330–395). The emperor Julian the Apostate (361–363) reopened hostilities after the death of Constantius but died after having reached the vicinity of Ctesiphon. His successor, Jovian (363–364), was forced to give up the Roman possessions on the Tigris, including Nisibis, and to abandon Armenia and his Arsacid protégé, Arsaces III, to the Persians. The greater part of Armenia then became a Persian province. Intermittent conflicts from Yazdegerd I to Khosrow I
After about two decades of disturbed reigns (Ardashīr II, Shāpūr III, Bahrām IV), Yazdegerd I came to the throne in 399. His reign is viewed differently by Christian and Zoroastrian sources. The former praise his clemency; the latter refer to him as “Yazdegerd the Sinful.” His initial inclination toward tolerance of Christianity and Judaism was met by resistance on the part of the nobility. Because of their attitude and because of the growing fanaticism of the Christians, Yazdegerd was forced to turn to repression. After his death (420) the nobles refused to admit any of Yazdegerd’s sons to the throne. But one of them, Bahrām, had the support of al-Mundhir, Arab king of Al-Ḥīrah (east of the lower Euphrates) and a Sāsānian vassal, and also, apparently, of Mihr-Narseh, chief minister in Yazdegerd’s last years, who was retained in office, and Bahrām eventually won the throne. As King Bahrām V (420–438), surnamed Gūr (for the onager, or wild ass), he became the favourite of Persian popular tradition, which exuberantly celebrates his prowess in hunting and in love. Unsuccessful in war with Byzantium (421–422), Bahrām V made a 100-year peace and granted freedom of worship to the Christians. In the east he did succeed in repelling an invasion by the Hephthalites. In the following decades, however (the second half of the 5th century), Hephthalite attacks continued to harass and weaken the Sāsānians. Fīrūz (reigned 457–484) fell in battle against them; his treasures and family were captured, and the country was devastated. His brother Balāsh (484–488), unable to cope with continuing incursions, was deposed and blinded. The crown fell to Kavadh (Qobād) I, son of Fīrūz. While the empire continued to suffer distress, he was dethroned and imprisoned (496), but he escaped to the Hephthalites and was restored (499) with their assistance. The Nestorian doctrine (claiming that divine and human persons remained separate in the incarnate Christ) had by then become dominant among the Christians in Iran and was definitely established as the accepted form of Christianity in the Sāsānian empire.
Kavadh I proved himself a vigorous ruler. He restored peace and order in the land. Amida was destroyed during his campaign against the Romans in 502, but another inroad by the Hephthalites in the east compelled him to ratify a peace treaty with the Byzantines. Toward the end of his reign, in 527, he resumed the war and defeated the Byzantine general Belisarius at Callinicum (531) with the support of al-Mundhir II of Al-Ḥīrah. Earlier in his reign he had moved away from the Zoroastrian church and favoured Mazdakism, a new socioreligious movement that had found support among the people. The crown prince, Khosrow, however, was an orthodox Zoroastrian; toward the end of his father’s reign, in collaboration with the chief mobed, he contrived to condemn the Mazdakites, who were destroyed in a great massacre in 528. On his father’s death, after acceding as Khosrow I (531–579), he concluded peace with the Byzantine emperor Justinian (532). He reestablished Zoroastrian orthodoxy, and, although some persecution of Christian communities occurred during periods of tension with Byzantium, the restoration of peace brought about a considerable amount of religious tolerance.