Adherents of Zoroastrianism use three distinct versions of traditional calendars for liturgical purposes. Those all derive from medieval Iranian calendars and ultimately are based on the Babylonian calendar as used in the Achaemenid Empire. Qadimi or Kadmi ("ancient") is a traditional reckoning introduced in 1006. Shahanshahi ("imperial") is a calendar reconstructed from the 10th century text Denkard. Fasli is a term for a 1906 adaptation of the 11th century Jalali calendar following a proposal by Kharshedji Rustomji Cama made in the 1860s.
A number of Calendar eras are in use: A tradition of counting years from the birth of Zoroaster was reported from India in the 19th century. There was a dispute between factions variously preferring an era of 389 BCE, 538 BCE, or 637 BCE.Allen's Indian Mail, and Register of Intelligence for British and Foreign India, China, and All Parts of the East, vol. 9 (1851), p. 303. The Directory & Chronicle for China, Japan, Corea, Indo-China, Straits Settlements, Malay States, Sian, Netherlands India, Borneo, the Philippines, &c, (1882), p. 37. The "Yazdegerdi era" (also Yazdegirdi or Yazdgerdi) counts from the accession of the last Sassanid ruler, Yazdegerd III (16 June 632 CE). This convention was proposed by Cama in the 1860s but has since also been used in conjunctions with Qadimi or Shahanshahi reckoning.Stephen Meredyth Edwardes, Kharshedji Rustamji Cama, 1831-1909: A Memoir (1923), 151f. An abbreviation "AY" ("Anno Yazdegirdi"?) is used in Parsiana 26 (2003), p. 1. A supposed abbreviation "Y.Z." is unknown in literature, but was introduced to Wikipedia ). An alternative "Magian era" (era Magorum or Tarikh al-majus) was set at the date of Yazdegerd's death in 652.Carol A Bromberg, Bulletin of the Asia Institute 17, Wayne State University Press (2003), p. 20. "Z.E.R." or "Zarathushtrian Religious Era" is a convention introduced in 1990 by the Zarathushtrian Assembly of California set at the vernal equinox (Nowruz) of 1738 BCE (−1737 in the astronomical year numbering).
History Achaemenid period
Calendrical traditions in ancient Iran can be traced back to the 2nd millennium B.C. Yet the earliest fully preserved calendar actually dates only from the Achaemenid Empire period, starting in the sixth century BC.
The Old Persian calendar, similar to the Babylonian calendar, was lunisolar, with twelve months of thirty days each. The Old Persian inscriptions mention only eight month names, so the other four names have been reconstructed from the Elamite transcriptions.Panaino, Antonio. Calendars, in Encyclopaedia Iranica, Vol. IV, Fasc. 6–7, pp. 658–677 (iranicaonline.org)
The Achaemenids used the lunisolar calendar at least until 459 B.C., because this is the date of the last preserved document using such a calendar.
The Babylonian calendar, being lunisolar, used an intercalary month roughly once every third year.Boyce, Mary (on behalf of the Persian Heritage Foundation). (1992). Zoroastrianism – Its Antiquity and Constant Vigour, p. 108. Mazda Publishers.Bickerman, E.J. (1968). Chronology of the Ancient World, p. 24. Thames & Hudson.
It is not clear exactly when the Zoroastrian calendar was first introduced. Nevertheless, because of its similarities with the Egyptian calendrical system, it can be hypothesized that its introduction was in the 5th century BCE, in the period during which Egypt was ruled by the Achaemenids. According to S. Stern, this happened during the first century of Achaemenid rule over Egypt, or from 525 to 430 BCE.
Scholars distinguish between the Old Avestan and a Later Avestan calendars. However, given that both have been reconstructed on the basis of similar sources, there are some disputes in this area.
The earliest Zoroastrian calendar follows the Babylonian in relating the seventh and other days of the month to Ahura Mazda.Boyce, Mary [ed. & trans.] (1984). Textual Sources for the Study of Zoroastrianism, pp. 19–20. University of Chicago Press.
In the civil calendar, intercalations did not always follow a regular pattern, but during the reign of Artaxerxes II (circa 380 BCE) astronomers utilised a 19-year cycle which required the addition of a month called Addaru II in years 3, 6, 8, 11, 14 and 19, and the month Ululu II in year 17 of the cycle.
A 365-day calendar, with months largely identical to the Egyptian calendar, was introduced shortly after the conquest of Egypt by the Achaemenid ruler Cambyses (c. 525 BCE).
Scholars are divided on whether this 365 day calendar was in fact preceded by a 360-day calendar of Zoroastrian observances.Boyce, Mary. (2005). Further on the Calendar of Zoroastrian Feasts. Iran (Journal of the British Institute of Persian Studies), XLIII, pp. 1–38
Hellenistic period Following Alexander's invasion of Persia in 330 BCE, the Seleucid (312–248 BCE) instituted the Hellenic practice of counting years from the start of a fixed era, as opposed to using regnal years.
The regnal era of Alexander is now referred to as the Seleucid era.
The Parthians (150–224 CE), who succeeded the Seleucids, continued the Seleucid/Hellenic tradition.Boyce, Mary. (1970). On the Calendar of Zoroastrian Feasts. Bulletin of the School of Oriental and African Studies, Vol. 33, No. 3, pp. 513–539. University of London and online at https://www.jstor.org/stable/614520 and http://www.essenes.net/pdf/On%20the%20Calendar%20of%20Zoroastrian%20Feasts%20.pdf
Parthian to Sassanid period In 224 CE, when the Babylonian calendar was replaced by the Zoroastrian, 1 Frawardin and the New Year celebration of Nawruz had drifted to 1 October. The older custom of counting regnal years from the monarch's coronation was reinstated. At this point the calendar was realigned with the seasons by delaying the epagomenal days by eight months (so that they now preceded the start of the ninth month) and adjusting the dates of the gahanbars (farming festivals) accordingly.
This caused confusion, since the new year now fell five days earlier than before, and some people continued to observe the old date. After 46 years (226–272 CE), with 1 Frawardin now on 19 September, another calendar reform was implemented by Ardashir's grandson Hormazd I (272–273 CE). During the first years after implementation of the new Gatha days, the population had not universally adopted the new dates for religious festivals, resulting in "official" celebrations takings place five days earlier than popular celebrations. In later years the population had observed the Gatha days, but the original five day discrepancy persisted. Hormazd's reform was to link the popular and official observance dates to form continual six-day feasts. Nawruz was an exception: the first and the sixth days of the month were celebrated as different occasions. Lesser Nawruz was observed on 1 Frawardin. 6 Frawardin became Greater Nawruz, a day of special festivity. Around the 10th century CE, the Greater Nawruz was associated with the return of the legendary king, Jamsed; in contemporary practice it is kept as the symbolic observance of Zoroaster's birthday, or Khordad Sal.
Mary Boyce has argued that sometime between 399 CE and 518 CE the six-day festivals were compressed to five days. The major feasts, or gahambars, of contemporary Zoroastrian practice, are still kept as five-day observances today.Stausberg, Michael. Die Religion Zarathushtras. Geschichte – Gegenwart – Rituale. Band (Volume) 3. Kohlhammer Verlag, 2004, pp. 66–67.
Medieval period
The Bundahishn, a treatise written in the early Islamic period (8th or 9th century) replaces the "Age of Alexander" with an "Age of Zoroaster", placed "258 years before Alexander" (consistent with the date given by Ammianus Marcellinus).Shahbazi, A. Shapur (1977), "The 'Traditional Date of Zoroaster' Explained", Bulletin of the School of Oriental and African Studies, 40 (1): 25–35, doi:10.1017/S0041977X00040386
By the reign of Yazdegird III (632–651 CE), the religious celebrations were again somewhat adrift with respect to their proper seasons. The calendar had continued to slip against the Julian calendar since the previous reform at the rate of one day every four years. Therefore, in 632, the new year was celebrated on 16 June.Parise, Frank. The Book of Calendars, 2nd Edition. Gorgias Press, 2002, pp. 96, 108–109, and 115–117. By the 9th century, the Zoroastrian theologian Zadspram had noted that the state of affairs was less than optimal, and estimated that at the time of Final Judgement the two systems would be out of sync by four years.
Calendar eras Zoroastrian Yazdegerd Era (Yazdegardi Era) starts on 16 June 632 CE. Yazdegird III was the last monarch of the Sasanian dynasty, and since the custom at that time was to count regnal years since the monarch ascended the throne, the reckoning of years was continued, in the absence of a Zoroastrian monarch, among some Zoroastrians.Zoroastrian Calendar. - zcserv.com
Zoroastrian dates are distinguished by the suffix Y.Z. for "Yazdegirdi Era". The usage "AY" is also found.ZCS website – Zoroastrian Calendar Services. https://www.zcserv.com/ – accessed 17 October 2011. Eduljee, K.E.. Zoroastrian Heritage: Zoroastrian Calendar. https://heritageinstitute.com/zoroastrianism/calendar/index.htm 2007–2011 – accessed 16 October 2011. Pithavala, Behram D.. True Zoroastrian Year: An invitation to think. 9 March 1963. https://www.heritageinstitute.com/zoroastrianism/pdf/pithavala.pdf – accessed 17 October 2011.
Yet another form of reckoning is the Zarathushtrian (Zoroastrian) Religious Era (Z.E.R./ZRE), adopted in 1990 CE by the Zarathushtrian Assembly of California. This is based on the putative association of the mission of Zoroaster with the dawn of the astrological Age of Aries, calculated for this purpose to have been the northern vernal equinox of 1738 BCE. Hence the year 3738 ZRE began in 2000 CE. The Zoroastrian community, both in Iran and in diaspora, have also been said to have accepted it, the former doing so in 1993 CE. A briefing paper from the Zoroastrian Trust Funds of Europe indicates that they recognise this usage to have been pragmatically adopted by Zoroastrians in Iran, while the diaspora continues to use the YZ system.Zoroastrian Festivals celebrated by Zoroastrian Trust Funds of Europe Incorporated, a briefing paper by the Zoroastrian Trust Funds of Europe.
Qadimi calendar The Qadimi (also Qadmi, Kadimi, Kudmi) or "ancient" calendar is the traditional calendar in use since 1006 CE.
In 1006 CE, the month Frawardin had returned to the correct position so that 1 Frawardin coincided with the northern vernal equinox. The religious festivals were therefore returned to their traditional months, with Nawruz once again being celebrated on 1 Frawardin.
The Julian Day Number corresponding to 16 June 632 CE is 1952063.
The Julian Day Number of Nowruz, the first day, of Year Y of the Yazdegirdi Era is therefore 1952063 + (Y − 1) × 365.
22 July AD 2000 was Nowruz and the first day of 1370 Y.Z. (or 3738 ZRE) according to the Qadimi reckoning.
In the Julian year 1300 CE, 669 Y.Z. began on 1 January, and 670 Y.Z. on 31 December of the same year.
Shahanshahi calendar
The Shahanshahi calendar (also Shahenshahi, Shahenshai, Shenshai) or "imperial" calendar is the system described in Denkard, a 9th-century Zoroastrian text. It explicitly acknowledged several methods of intercalation: a leap-day every 4 years; adding ten days every 40 years; a leap-month of 30 days once every 120 years; 5 months once every 600 years; 1,461 Zoroastrian years equal 1,460 Julian years.
The Denkard then states: