Another trend that developed in the Sāsānian period, although it had already made itself felt under the Arsacids, was a strict principle of dynastic legitimacy. For a usurper not of the royal blood to come to the throne was an extremely rare occurrence, though it was in fact accomplished by Bahrām VI Chūbīn in 590. Loyalty was given, however, to the whole royal house, rather as it was in the later Ottoman Empire. The person of the individual ruler was a matter of comparatively lesser importance, and one member of the dynasty could readily be removed and replaced by another. In accordance with this principle of legitimacy, Persian tradition carried the Sāsānian line back to the Achaemenids and, ultimately, to the kings of the legendary period. Religious developments Zoroastrianism
The ancestors of Ardashīr had played a leading role in the rites of the fire temple at Istakhr, known as Ādur-Anāhīd, the Anāhīd Fire. With the new dynasty having these priestly antecedents, it seems only natural that there would have been important developments in the Zoroastrian religion during the Sāsānian period. In fact, the evolution of Zoroastrianism as an organized religion into something resembling its modern form can be regarded as having begun in this period. Under the Parthians, local magi (priests) had no doubt continued to perform the traditional ceremonies associated with the old Iranian deities, the fire cult, the creed preached by Zoroaster, with its emphasis on the worship of Ahura Mazdā, and even the cults of cosmopolitan deities that were introduced in the Hellenistic period and later.
Under the Sāsānians, stress was increasingly placed on the fire cult and the worship of Ahura Mazdā. Strong mutual relationships, furthermore, were developed between religion and the state, and an ecclesiastical organization was set up in which every local district of any importance had its own mobed (“priest”; originally magupat, “chief priest”). At their head stood the mobedān mobed (“priest of priests”), who, in addition to his purely religious jurisdiction, appears, especially in later times, to have had a more or less decisive voice in the choice of a successor to the throne and in other matters of state. There is also some evidence that the mobeds, by virtue of their proficiency in reading and writing in general and in the interpretation of the sacred scriptures in particular, performed the duties of registrars and scribes in semireligious or nonreligious matters, like the Christian clergy in medieval Europe. This situation in turn makes it likely that the priestly library buildings not only contained the sacred texts, charters, and other church records but also served as repositories of local archives, title deeds, and other documents of a legal nature. The building known as Kaʿbe-ye Zardusht and referred to as a bun-khānag (“foundation house”) may well have served this very purpose.
In the matter of religious practice, the theology of the Sāsānians appears to have developed from that of their home province of Persis. There, extraneous religious influences were limited. The opposition between the good spirit of light and the demons—between Ahura Mazdā (Ormizd) and Angra Mainyu (Ahriman)—remained the essential dogma. All the other gods and angels were restricted to the role of subordinate servants of Ahura Mazdā, whose highest manifestation on earth was not so much the sun or the sun god Mithra (Mihr) but rather the holy fire guarded and attended by his priests. At the same time, the names of such deities as Verethraghna (Wahrām), Mithra, and Anāhitā (Anāhīd) were still associated with the names of fire temples or classes of fires. Divine names were also used to designate the 30 days of each month and of the 12 months of the year, plus five epact days, called gahānīg, to align the lunar with the solar year.
All the prescriptions of purity were scrupulously observed. The elaborate ritual still maintained in modern times by the Parsi for the purification and custody of the sacred fire was no doubt observed under the Sāsānians. The officiating priest was girt with a sword and carried in his hand the barsman (barsom), or bundle of sacred grass. His mouth was covered to prevent the sacred fire from being polluted by his breath. The practice of animal sacrifice, abhorred by the modern followers of Zoroaster, is attested for the Sāsānian period at least as late as the reign of Yazdegerd I (399–420). On the days of the important festivals, such as Nōgrūz (Nōrūz), the first day of the vernal equinox, and on the day of Mihragan (the 16th day of the seventh month), the sacred fire was displayed to the faithful (wehden) at nightfall from some vantage point. Under the Sāsānians the injunction not to pollute the earth by contact with corpses but to expose the dead on mountaintops to vultures and dogs was strictly observed. Ahura Mazdā preserved his character as a national god who bestowed victory and world dominion on his worshipers. In rock-relief sculptures he appears on horseback as a god of war.
Theology was further developed, and an attempt was made to modify the old dualistic concept by considering both Ahura Mazdā and Angra Mainyu as emanations of an original principle of infinite time (Zurvān). This doctrine enjoyed a certain degree of official recognition in early Sāsānian times. In the reign of Khosrow I (531–579), however, the “sect of the Zurvānites” was declared to be heretical. The chief trend of Sāsānian religion, apart from the process of being institutionalized, was toward elaborating its ritual and doctrine of purity. A complete and detailed system of casuistry was developed, which dealt with all things allowed and forbidden and with the forms of pollution and the expiation of each. One of the consequences of this development was that increasing emphasis was placed on orthodoxy and rigorous obedience to priestly injunctions. Nonorthodox and heretical cults and forbidden manners and customs came to be regarded as a pollution of the land and a serious offense to the true God. It was the duty of the believer to combat and destroy the unbelievers and the heretics. In short, the tolerance of the Achaemenids and the indifference of the Arsacids were gradually replaced by religious intolerance and persecution.
Despite his priestly family origin, Ardashīr himself seems not to have been the person responsible for initiating these new directions in religious affairs. It was once believed that the institutionalization of the Zoroastrian church and the codification of its scriptures and beliefs were the work of a high priest named Tansar, a contemporary of Ardashīr I, of whose activities an account is preserved in the Letter of Tansar, contained in the History of Ṭabaristān (Tārīkh-e Ṭabaristān) by the Persian writer Ibn Isfandiyār (flourished 12th–13th century). New inscriptional evidence, however, suggests that, if Tansar was, in fact, a historical personage, his role in religious matters was overshadowed by Kartēr (Karder). The latter, an ehrpat (or herbed, “master of learning”) and mobed (or magupat, “priest”) already prominent under Shāpūr I, appeared during the reigns of Bahrām I (reigned 273–276) and Bahrām II (276–293) as the dominant figure in the Zoroastrian church. As stated in the Kaʿbe-ye Zardusht inscription of Kartēr, he claims credit for suppressing non-Zoroastrian religious communities in Iran (“and Jews, Buddhists, Brahmans, ‘Nazoreans,’ Christians…were struck upon”), imposing orthodoxy and discipline on the priesthood (“the heretics [ahlomog]…who in the Magus estate did not attend to the Mazdean religion and the services to the gods with discrimination, I struck them with punishment and I castigated them”), and establishing royal foundations for the maintenance of priests and of sacred fires. (See also Zoroastrianism.) Christianity