Tropical Solar Zoroastrian Calendar (Part II)

Indo-Iranian Calendars And Intercalation

By: Ali A. Jafarey


Vedic Calendar:

It may be noted that the Indo-Aryans had also six seasons (Sanskrit rtu, Avestan ratu) evidently modified to meet the climate in the Indus Valley. They were: Vasanta (Spring), Grishma (Summer), Varsha (The Rains), Sharad (Autumn), Hemanta (Winter), and Shishira (the Cool season).

Persians and Other Iranian Calendar:

The Achaemenians, Sogdians, Chorasmians, and Armenians, all Zoroastrians by faith, had their own names for their months. The names of the Achaemenian months, as given in the bas-reliefs of Darius the Great are rendered to convey: (1) Irrigation-canal-cleaning month, (2) Vigorous spring, (3) Garlic-collecting month, (4) Hot-step, (7) God-veneration, (8) Wolf-birth, (9) Fire-veneration, (10) “Anâmaka — Nameless” month, and (12) Digging-up. Three names have not been given in Old Persian but we have their Elamite pronunciations and all, except two, are nonreligious terms. The Achaemenians had numbers instead of names for the days of the month. (see Old Persian, Ronald G. Kent, 2nd ed., New Haven, 1953). That confirms that the months as well as the days named after pre-Zarathushtrian deities and post-Zarathushtrian personifications of Gathic abstracts is a later addition. There are indications that it was done during the reign of Artaxerxes II (405-359 B.C.E.), and that naming the months and days in honor of deities were adopted from the Egyptians.

The names of the Gahanbars, and those of the Vedic, Achaemenian, Sogdian, Chorasmian, and Armenian months show that the names of the pre-Zarathushtrian and Gathic months must have been based on the seasons and social activities, and not on deities. These old names have, however, been so well obliterated by the authoritarian priests that we do not have any inkling of what they were.

Later Avestan Calendar:

The names of the twelve months in modern Persian and their Avestan forms with their corresponding Zodiac names are:

1. Farvardîn Fravashi/Fravarti Aries 21 March

2. Ardîbehesht ASHA VAHISHTA Taurus 21 April

3. Khordâd HAURVATÂT Gemini 22 May

4. Tîr Tishtrya Cancer 22 June

5. Amordâd AMERETÂT Leo 23 July6. Shahrîvar KHSHATHRA VAIRYA Virgo 23 August

7. Mehr Mithra Libra 23 Sept.8. Âbân Ap Scorpio 24 Oct.

9. Âzar ÂTHRA Sagittarius 22 Nov.

10. Dey Dathva Capricorn 22 Dec.

11. Bahman VOHU MANAH Aquarius 21 Jan.

12. Esfand(ârmaz) SPENTÂ ÂRAMAITI Pisces 20 Feb.

Note: Of these only those in capital letters are the Gathic “Primal Principles of Life,” Âzar/Âthra has been mentioned in the Gathas as the symbol of the Progressive Mentality (Spenta Mainyu), and “ap” (water) is also mentioned in the Gathic texts, but the rest are later Avestan names.


The Pahlavi books of Denkard and Greater Bundahishn confirm that:

1. There are two Zoroastrian calendars: (a) A tropical year calendar of 365 days 5 hours and 48 minutes that is precisely calculated to begin on vernal equinox, and (b) a layperson calendar of 365 days that is intercalated by one day every 4 years in normal times, and by 10 days after 40 years, one month after 120 years, five months after 600 years or one year after 1440 years in abnormal times. The intercalary hours must be precisely calculated to make a full day, month or year. The intercalary is necessary for (the right performance of) Nowruz, Mehregân, and other time-honored Jashans.

2. The year begins with vernal equinox (on about 21 March).

3. Spring lasts from the beginning of Aries to Gemini (on about 21 March to 21 June), summer from Cancer to Virgo (on about 22 June to 22 September), autumn from Libra to Sagittarius (on about 23 September to 21 of December), and winter from Capricorn to Pisces (23 December to 20 March). (DENKARD (Acts of Religion), Book 3, Peshotan Dastur Behramjee Sanjana, 1900, and Greater Bundahishn, Chapter 25, Behramgore Tehmuras Anklesaria, Note by AAJ: The full texts may be read by visiting Mr. Joseph Peterson’s and clicking the above references.)

The Late Vada Dasturji Hormazdyar K. Mirza on Intercalation:

Shahenshahi, Qadimi, Fasli

At present there are three sects or groups among the Parsis of India

(1) Shahenshahi ‘of imperial (reckoning)’. (2) Qaadimi ‘of ancient (reckoning)’. (3) Fasli ‘of seasonal (reckoning)’.

These three groups are formed on the basis of the differences in calendar and time-reckoning, and the consequent differences in the dates of observing the new year day and other festivals.

In the second system of time-reckoning (Sal Vihezakik), as noted above, a month was intercalated every 120 years. In ancient Iran, this intercalation was affected under royal patronage according to the guidance and advice of the council of the learned men of the realm. Al-Biruni writes (p. 54):

“The reason was this that intercalation was an affair settled under the special patronage of their kings at a meeting of mathematicians, literary celebrities, historiographers, and chroniclers, priests, and judges, — on the basis of an agreement of all those regarding the correctness of the calculation, after all the persons I have men­tioned had been summoned to the royal court from all parts of the empire, and after they had held councils in order to come to an agreement.”

The last intercalation under Iranian sovereignty was affected in 406 A. C. during the reign of Sasanian Emperor Yazdgard I (399-420). On this occasion, two months were intercalated–one that was due and the other in anticipation of troubled time in the coming century when the next intercalation was due. In 406, therefore, the five Gatha days were transferred from after the end of Shahrevar month and were placed after the end of Avan month, where they remained for six centuries thereafter. Due to political instability and disorder in Iran, and later the Arab invasion and overthrow of the Empire, the practice of intercalation fell into disuse.

In 1006 A. C. four intercalations were due; and it appears that in that year four months were intercalated, and the Gatha days, which were after the end of the Avan month at that time, were shifted and placed after the end of the 12th month Aspandarmad. Hence the Oshmurtik year coincided with the Vihezakik year. Since then there was no difference between the two systems, or really speaking only the Oshmurtik year remained in practice.

The difference of a month in various Zoroastrian calendars in Iran, and also between the Zoroastrian calendar of Iran and that of India had been noticed in various sources. This difference of a month between the Zoroastrian calendar of Iran and that of India was stressed and highlighted in 1721 when Jamasp Velayati, a Parsi priest of Iran, came to Surat. The matter came to a head when Jamshid, a Zoroastrian of Iran, came to Surat in 1736. He explain­ed that the Zoroastrians of Iran were ahead of their co-religionists in India by a month in commencing their year and observing religious festivals and functions. Some Parsi families of Surat adopted the Iranian system of reckoning the year, as explained by Jamshid. In order to bring their calendar in conformity with that of Iran, a month was dropped from 1114 A. Y. (1745 A. C.), by reckoning Roz Mahraspand of Mah Avan (of Indian Parsi calendar) as Roz Mahraspand of Mah Adar. Thus they formed a separate sect or group for themselves (1745 A. C.). They were known as Qadimi ‘of the ancient (reckoning)’. This is an Arabic term used in Mod. Pers. in the sense of ‘ancient, former’. It was used by the Zoroastrians even before 1745. The corresponding term used in Iran is bâstâni ‘ancient’. The Qadimis adopted also the Iranian mode of prayers, customs, and ceremonies, which differ to some extent from those of their other co-religionists in India.

The Zoroastrians of India who continued to follow their origi­nal system of reckoning the year are known as Shâhenshâhi ‘of the Imperial (reckoning)’. Evidently this term refers to the Sasanian Emperors, particularly Yazdgard III, the last Sasanian Emperor.

The said difference of one month between the Zoroastrian calendar of India and that of Iran may be explained by the assump­tion that the forefathers of the Zoroastrians of India intercalated a month after the downfall of the Sasanian Empire either in Khora­san (where they lived in exile) or after their arrival in India. Evidently, this must have happened after 1006 A. C. and in India. But no record or even oral tradition has been preserved.

Jashn of Awardâdsâlgâh

It appears that the Jashn of Awardâdsâlgâh gives a clue to the solution. This Jashn was performed every year on Roz Khordad Mah Aspandarmad of the Shahenshahi reckoning. It was perfor­med only in India, and only by the Shahenshahi priests. It was not performed by the Qadimi priests, and it was unknown in Iran. The day on which the Jashn was performed coincided with the new year day of the Iranian and Qadimi reckoning. It is reason­able to conclude, as done by M. P. Khareghat, that the Jashn was instituted when the last intercalation of a month was affected by the forefathers of the Parsis of India in remembrance of the new year day which was abandoned when the intercalatory month was added. However, Khareghat’s explanation of the term is not satisfactory. ….

Hence it is reasonable to conclude that ‘Awardadsalgah’ was originally ‘Khordadsalgah’; the day was called sâl-gâh ‘time of (new) year’ in remembrance of the new year day which was abandoned; and Roz Khordad was the day of the intercalated month on which it was so abandoned. Hence the term ‘Awardadsalgah’ must be `Khordadsalgah’, and it should mean: ‘the time of the (new) year (falling on) Khordad (Roz)’; and the Jashn was instituted by the Parsis of India in remembrance of the Noroz, which they abandon­ed while intercalating a month in India. (Outlines of Parsi History, Hormazdyar Dastur Kayoji Mirza, Bombay, 1974, ages 442-445)

Part III:


By: Ali A. Jafarey

This I ask You, tell me truly, Lord.
Who is the foremost creator and parent of the Universal Law?
Who made the sun and the stars in their paths?
Who makes the moon wax and wane?
I am, Wise One, eager to know all this and more.
(Gathas: Song 9.3)

Any person with a fair knowledge of astronomy will at once recognize that this stanza was composed by a person who must have been well versed in astronomy and that it speaks of a precise lunisolar year. This is clear because (1) Zarathushtra speaks of Asha, the law of precision which governs each and every movement by any body, macro or micro, in the universe; (2) he speaks of the paths of the sun and the stars, i.e. the tropical and sidereal movements; (3) lunar phases provide the lunar month in two parts of waxing and waning of moon; and (4) there is a desire to know more in this and other scientific fields. This opens the way for continuous research to understand the creation and the Creator. It means constant improvements in calendar and other necessities of life.

Lunisolar Calendar

We know from the Vedic lore that the Aryans, like many nations of their day, followed lunisolar year. The Avesta confirms this. The lunar month had two parts: the waxing period and the waning period, each of about fifteen days. That made the year fall short by five days. But the lunar month is 29.53058 days. Therefore, the difference of 23 hr 15 min 57.5 sec or approximately one day every two months plus the five days short, making a total of almost 11 days, were made good by intercalations of one month every 30 months. However, as reflected by the Vispered, the early Zarathushtrians added about 11 days at the end of the year. This shows that an improvement was made, evidently by Zarathushtra himself, in the Indo-year calendar of the pre-Gathic age.(1)

We do not know the names of the months of the pre-Zarathushtrian and Gathic periods. However the names of the four seasons, the six Gahanbars, the Vedic months, and the Achaemenian months are generally based on various phases of the seasons. It is significant, however, that none of these bear the names of any Aryan deity. They only reflect the people adjusting themselves with the changing phases of the year. The Gathic months must have followed the same pattern, particularly when the Gâhânbârs, the most revered festivals, bear seasonal names. This shows a lunisolar year, with months named after seasonal changes, that was intercalated to keep it precise .(2)

Solar Calendar

Later Avesta shows that the calendar was turned into a full solar year with each month having 30 days. We know the names of only five months from the extant Avesta–Ardibehesht, Tir, Shahrivar, Mehr, and Dey–and these from a late composition, the Âfarînegân-e Gâhânbâr.(3) The names of the thirty days are also mentioned together in only one Yasna section–Yasna 16.3-6. The two Sirozahs are but thirty quotations from the Avesta arranged in the order of the days of a month. The last five days of the year and an evident fraction kept the year in tune with the seasons.

The Avestan words yârê for a “year” or “year of 365 days” and saredha for a “year of 365 days 5 hours and fraction” show that while the common people maintained a simple way of reckoning the year, the astronomers-in-charge kept the tropical year in count and the religious festivals of Gâhânbâr in line with the seasons. These are the ushmurtik (365 mean solar days) and vehizakîk (365.2422454 mean solar days) calendars of the Sassanian and post-Sassanian times. Vichitakihâ-i Zâdspram of the 9th century CE tells us to observe Zarathushtra’s death anniversary according to the vehizakîk calendar.(4)

Erring Eras

This reckoning of the religious year was kept alive until a new custom was copied by Iranian courtiers from Babylonian and other prevailing traditions which reckoned the year from the ascension of each ruler to the throne. This was attractive and pleasing for the kings surrounded by flattering courtiers. The practice began as early as the Achaemenians and came to end when the Sassanian Empire fell before the invading Arabs some 1400 years ago. It has distorted and disturbed chronologies to such an extent that Iranian historians have no record of the end of the Kayanian age, as to who were their successors, the entire Achaemenian line with the exception of Darius I and Darius III, the Parthians as empire builders, and the Kushans in Khorassan and India. The history as reflected in Sassanian writings and the subsequent Arabic and Persian writings by Iranians of the post-Sassanian period, including the famous Shahnameh, have many an important event missing in Iranian history. The historic events have been, no doubt, preserved but because of the lack of a chronological order and the missing eras, they are haphazardly included in the now “legendarized” Pishdadian and Kayanian periods. The practice of remembering an era by the ascension of a king continues to linger in the Yezdgerdi year observed by Parsis and some Iranian Zartoshtis. It reminds one of the ascension of an ill-fated monarch, not the dynamic message of the renovating Master, Zarathushtra. In fact, the Zoroastrians did not have a “religious” era during the entire “imperial” period, from the Achaemenians to the Sassanians. The Zarathushtrian Religious Era was completely forgotten except the early events of the Gathic period, preserved in the Vichitakihâ-i Zadspram.

Nevertheless the tropical year, called saredha in Avesta and vehizakîk in Pahlavi continued until or even beyond 9th century CE and kept the religious festivals and their relevant agricultural and administrative activities in step with the seasons. However, it appears that during the last days of the Sassanians, the turbulent conditions made the authorities forget the four-year intercalation of the ushmurtik calendar and it was haphazardly done, in an on-and-off period of 120 years. It is this intercalation, and not the four-year one, which is reflected in the post-Sassanian Arabic and Persian books, and not the Avestan and Pahlavi writings, that has caused the misunderstanding that the Sassanians and earlier dynasties practiced the 120-year intercalation on regular basis.

With the disappearance of astronomer leaders, the common Zoroastrian priests and laymen relied more and more on the ushmurtik method and in the course of time, lost the track of vahizakîk and intercalation. Today, the Shahenshahi and Qadimi calendars, one month apart and beginning in July and August, show that no intercalation has taken place for approximately 825 years.

New Tropical Calendar

After the fall of the Sassanian empire, the Arabs imposed their Hegira era with its revolving lunar months. It soon proved its impracticality. Iranian experts, both Zoroastrian and Muslims, helped the authorities but not very successfully. As a consequence farmers, most of whom were still Zartoshtis, suffered losses because of off-season taxes. Finally, Iranian astronomer-scientists, including the famous Omar Khayyam, succeeded in getting the tropical year, now called Jalâli, after Sultan Jalâl al-Din Malekshah Saljûqi (1072-92 CE), the ruler, formally declared. It is this improved and advanced tropical year which is the official calendar of Iran and Afghanistan. The formalization of the ancient Iranian calendar was a great achievement, an achievement which was kept alive not only by the rulers of the Greater Iran, from the Iraqi borders to the Chinese

Zarathushtrian Religious Era

The Pahlavi “Vichitakiha-i Zadspram” gives the dates of certain events in the Gathic period in the “Year of Religion.” But, the question is: When did it begin?

Scholars of Zoroastrianism have been fixing the date of Zarathushtra from the 6th century to 17th century B.C.E. Some enthusiasts have even gone back as far as 8,000 or more years. Thus Zarathushtra ranges from a contemporary to the Achaemenians to a man of the Old Stone Age. All this discrepancy is due to the fact that every scholar has taken only one point, or perhaps two, to pinpoint the age. One scholar supposes that Vishtaspa, father King Darius the Great, was the same Vishtaspa, the royal companion of the Sage, and therefore makes him live around 500 BCE. The other relies solely on the tradition reported by Iranian writers, such as Abdul-Rahman Biruni, who himself is perplexed by discrepancies in Sassanian and earlier chronology. The other takes the Greek report that he lived 6000 years before the Trojan War, estimated to have been fought in 1200 BCE. Religious prejudices by aliens have brought him as close as possible to present days because of his dynamic message. How could it be so old as to outdate the relevant founders of their religion! Religious enthusiasm by Zoroastrians have pushed him as far as they could, just to show off that their “prophet” is the foremost in conveying the divine message [to Stone Age people].

However, the combined attempts of room-scholar philologists and historians, and field-scholar archeologist and anthropologists have narrowed the age to 1000 to 1700 BCE. Whatever, the date, there are proofs that he lived in the Vedic, rather Rig Vedic age, 2000 to 1500 BCE.(5)

Meanwhile, recent astronomical researches have helped to fixed many legendary dates in a more accurate way. One such instance is Zarathushtra’s date. The late Zabih Behruz, an Iranian scholar and mathematician, came, by studying various astronomical data and the disparities in the reported chronologies, to the conclusion that Zarathushtra, himself an astronomer, timed the conversion of Kavi Vishtaspa and his court to coincide with the entrance of Aries in the vernal equinox. Zabih calculated the day to have occurred on 1st of Farvardin, 21st March 1725 BCE. Since Zarathushtra declared his mission on this very day 12 years before, the Zarathushtrian Religion Era began in 1737 BCE. This gives us, at least a conventional date, within the Rig Vedic period, as a fair solution of the dates between 1000 to 1700 BCE.(6)

ZRE Restored

It appears that the religious era, maintained during the first 300 years of the Good Religion, fell in disuse because of disturbed days that followed the Kayanian fall. However, today we know that it began on the vernal equinox of 1737 BCE. The Zarathushtrian Religious Era is, therefore, 3743 now.

The writer used the Zarathushtrian Religious Era in his writings since 3717 = 1979. The Zarathushtrian Assembly accepted it since its establishment in 1990. Iranian Zoroastrian Publications like the Bulletin of the California Zoroastrian Center, Los Angeles and “Peik-e Mehr” of Vancouver, Canada also began publishing the era. And now, it is a great pleasure to see that the Zartoshtis in Iran have also adopted it, and it is displayed in most of their publications. It is hoped that others will join the move.

It gives one the proud pleasure of constantly knowing the age of the dynamic Divine Message of Asho Zarathushtra–3743 years and more as the time passes. The Zarathushtrian Era, begun by Zarathushtra and followed by his companions, started as a reformed lunisolar calendar, was improved and changed into a true tropical calendar by later Avestan astronomers, was faithfully followed as the vehizakîk by the Sassanian rulers despite the tradition of “ascension eras,” was revived and further improved by Iranian scientists of the post-Sassanian period, and now stands restored and in line with Zarathushtra’s wish to “know all this and more.” Astronomically and practically, it is the most perfect calendar in the world. Let us promote it.

(1) The Vispered (lit. “all-the-precise-times-of-prayers,” All-the-Festivals) concerns the Gahanbars and the 11-day intercalary days of prayers at the end of the lunisolar calendar. The Vispered is not, as generally believed, secondary to the none-Gathic Yasna. It is older and in its unadulterated form, reflects the Gathic festivals only. The non-Gathic Yasna belongs to the rites and rituals of the later Avesta. See “Three Distinct Aspects of the Avesta,” The Ancient Iranian Cultural Society Bulletin, Tehran, Vol. 7, No. 1, March 1969 and Gâh-shomâri-ye Avestâyee (The Avestan Calendar), both by Jafarey, Persian monthly Yaghmâ, Tehran, No 9, month of Âzar and No. 10, month of Âban, 1335 (November and December 1976).
(2) (a) Seasons: Zarema/Vasanta (spring), Hama/sama (summer), zima/hima (winter), and sareda (?)/sharada (autumn). The first form is in Avesta and the second in Sanskrit.
(b) Gâhânbâr (seasonal festivals): (1) Hamaspathmaidhaya (vernal equinox), (2) Maidhyoi-zarema (mid-spring), (3) Maidhyoi-shema (mid-summer), (4) Paitish-hahya (harvest), (5) Ayâthrema (no-travel [season]), and (6) Maidhyâirya (mid-year).
(c) Vedic months: (1) Madhu (pleasant, spring), (2) Mâdhav (pleasantly, vernal), (3) Shukra (bright), (4) Suchi (glowing), (5) Nabhas (cloud), (6) Nabhasya (cloudy), (7) Isha (sappy), (8) Ûrja (sap), (9) Sahas (powerful) , (10) Sahasya (powerfully), (11) Tapas (warm), (12) Tapasya (warming). The names show that the calendar was reformed to conform with the weather in India.
(d) Achaemenian months: (1) Adukanaisha (canal-cleaning?), (2) Thûravâhara (full-spring), (3) Thâigarchish (garlic-collecting ?), (4) Garmapada (hot-step), (5) Thurnabshish (fully-humid), (6) [Karbashiash?], (7) Bâgayâdish (god-veneration), (8) Varkazana (wolf pack. Perhaps an allusion to appearance of wolves in autumn), (9) Âshiyâdiya (fire-veneration). Note its relation with the month of Âzar, month of Fire), (10) Anâmaka (nameless), (11) [Samiamash?], (12) Viyaxna (ploughing).
(3) Âfarin-e Gâhânbâr 7-12.
(4) Zarathushtra passes away in the 47th year of Religion at the age of 77 years and 40 days in the month of Ardibehesht on the day of Khûr of the vehizakîk (calendar) and it has been taken to the month of Dey, day of Khûr. But the prayer rite is only in the month of Ardibhesht. (Vichitakihâ-i Zâdsparam, Section 25, B.T. Anklesaria, Bombay, 1964)
(5) Prof. Shahpur Shahbazi, The Traditional Date of Zoroaster, BSOAS, XL, Part I, 1977 p. 25-35
(6) Zabih Behruz, Taghvâm va Târîkh dar Iran, Tehran 1952. Dr Ali Hassuri, The Date of Zoroaster, in The Avesta and Modern Art, Tehran, 1978.