The early progenitors of today's Zoroastrian community were nomads who had a keen perception of the seasonal changes and a deep respect for the elements of Nature. In their innate wisdom they chose to start the New Year on the day of Vernal Equinox (March 21) which marks the beginning of spring in the Northern Hemisphere. Also, on this day the sun enters the constellation Aries and is directly over the equator making the day and night equal.
Ancient Zoroastrians observed a 360 days Calendar of 12 months with each month comprising of 30 days. The months were named after seasonal festivals but the days of each month were merely numbered from one to thirty. New Year was celebrated on the day of Vernal Equinox and to keep the 360 days Calendar in harmony with the seasons, a thirteenth month was intercalated every six years. Since each year the spring season brings the resurgence of life in Nature, the first day of Spring was deemed to be the day of renewal, hope and joy and was celebrated as Noruz (New Day).In the middle of the fifth century BCE, during the Achamenian era, a distinctive 360 days Calendar was created. Each day (Roz) of the twelve months was assigned to an Amesha Spenta or Yazata; while all the months, except the first and tenth, were assigned to the Yazatas. The first month, Fravadin, was assigned to the Fravashis and the tenth month, Dae, was named for the Creator. Each month (Mah) was divided into four parts which began with a day dedicated to the Creator.
These days were:
day 1 Roz Hormuzd first day of the month dedicated to the Creator
day 8 Dae-pe-Adar day (prior to Roz Adar) dedicated to the Creator
day 15 Dae-pe-Meher day (prior to Roz Meher) dedicated to the Creator
day 23 Dae-pe-Din day (prior to Roz Din) dedicated to the Creator
Da in the prefix Dae is the root of the word Datar (Dadvah) which means Creator. There were also six seasonal festivals, known as the Gahambars. These were associated with the agricultural seasons and to this day, we celebrate each Gahambar by performing a Jashan and thanking Ahura Mazda for the seasons and the beautiful creations.
Since the Achamenians, along with the Babylonians, followed a 360 days Calendar, they had to intercalate one month every six years. However, the Egyptians of that era had a Calendar based upon a 365 days solar cycle. In 46 CE (Common Era) the Romans adopted the Egyptian Calendar but the Persians kept on following the 360 days Calendar until the middle of the third century CE .
The earth revolves around the sun in exactly 365 days, 5 hours, 48 minutes and 46 seconds. The 365 days Calendar lost almost a 1/4 day each year and in order to compensate this loss, the Roman Emperor, Julius Ceasar, adopted to intercalate one day every four years and called that year a leap year. This procedure created an opposite effect of increasing 11 minutes and 14 seconds per year which amounted to 7 days in 1000 years. In order to bring the Julian Calendar closer to the natural solar year, in 1582 Pope Gregory XIII, on the advice of astronomer Christoph Clavius, promulgated in 1582 that no centennial year should be leap year unless exactly divisible by 400. Thus 1700, 1800, 1900 were not leap years but the year 2000 will be one. While most of Europe accepted the reformed calendar in 1582, England and its colonies (including USA) only adopted the new calendar in 1752 and till that time the year was calculated from Vernal Equinox to Vernal Equinox and March was the first month. In 1752 the New Year day in England was shifted from the Vernal Equinox (which fell on Mar 25 according to the old calendar) to Jan 1. Thus they broke with the time-honored custom of celebrating the New Year Day on the Vernal Equinox and this Calendar which is followed to this day is called Gregorian.
A major revival of the Zoroastrian religion took place in 226 CE when the first Sassanian King Ardeshir came to the Persian throne. He changed the old 360 days Calendar to 365 days by adding five extra days which were piously dedicated to the five Gathas of Zarathushtra. Ardeshir's Calendar reforms had a far-reaching effect on his people who initially rejected his new Calendar as it affected their religious sentiments. This resulted in two Calendars, one decreed by the king and the other, older one, followed by the majority of the people in the kingdom.
Traditionally, the Fravashis were welcomed to the physical world on the last day of the old year, when the festival of FRAVARDIGAN (Muktad) was observed. After spending the night and receiving the veneration of the descendants the Fravashis were bid farewell on the following dawn, and at sunrise the New Year (Noruz) was brought in. At the end of the first year, the king's new Calendar fell behind the people's older Calendar by five days. The Muktad days had to be extended because it was believed that the Fravashis could not return to their spiritual world until the dawn of the Noruz. The king celebrated Noruz on the sixth day of the people's Calendar. This day was called KHORDAD SAL, meaning Greater Noruz. At the end of the second year the King declared that Noruz must be celebrated only at the end of 365 days and so the people were made to add 5 more days to their old Calendar. This created more confusion with some people observing the Muktad for 5 days while others for 10 days. Later on a compromise was reached and it was decided to synchronize the two Calendars by maintaining the festival of Fravadigan for 10 days; however, some traditionalist extended the Muktad period to 18 days.
The change, from 360 to 365 days, in the Persian Calendar reduced the difference of 5 1/4 days from the natural solar year to less than a 1/4 day each year. The traditional intercalation of a thirteenth month every six years was no longer warranted. However, to account for the loss of a 1/4 day each year it was necessary to intercalate one month every 120 years. This was completely ignored and the day of Noruz was left to recede from the day of Vernal Equinox. By the end of the 6th century CE it had slipped away to July instead of occurring in Spring.
The Shenshai Calendar dates back from the year 631 CE when the last Zoroastrian King, Yazdazard III, ascended the throne. After his defeat in the battle of Nehavand in 641 CE, the Zoroastrian empire was conquered by the Arabs and within a few centuries the Zoroastrian community gradually got disintegrated. A group of Zoroastrians migrated to India and came to be known as Parsees.
In the year 1006 CE the roaming Noruz day again coincided with the day of the Vernal Equinox. There was great rejoicing both in Iran and India. It was resolved that Zoroastrians must add an extra month every 120 years. Between 1126 and 1129 CE, the Parsees in India remembered and added a 13th month called the 2nd Spendamad but the Zoroastrian in Iran forgot. The intercalation made by the Indian Zoroastrian Community, put the Calendar of the Iranian Zoroastrians ahead by one month. This difference between the two Calendars went unnoticed until a learned Kermani priest, Dastur Jamasp Vilayat, visited India in 1720 and brought it to the attention of the Parsi community. Long after the Dastur had left, the Zoroastrians in India continued to debate the issue of the two Calendars. In 1746, a group of Zoroastrians in India decided to adopt the Iranian Calendar as that of the "old time". They separated and formed a new group called Qadimi but the majority of Parsees continued to follow their traditional Calendar and called themselves Shenshais (Royalist). No intercalations have been made since 1130 CE.
The Shenshai and Qadimi Calendars do not have any means of intercalation built into them. Consequently, in both these Calendars, Noruz recedes from the day of Vernal Equinox and the Gahambars, the seasonal festivals, are celebrated at the wrong time of the year.
According to tradition, Noruz has been associated with King Jamshed who, it is said, ruled the world during a "golden age" which will once again be restored at the end of time. The prefix Jamshed was added to the word Noruz in the late nineteenth century and since then the festival of the first day of Spring has been called Jamshedi Noruz by the Parsees..
In the early twentieth century, Khurshedji Cama, a well-known Zarathosthi of Bombay attempted to tackle the problem of unifying the Zoroastrian Calendars. He was convinced that the original Zoroastrian Calendar was created to be in harmony with the seasons. In 1906, he formed the Zarathosthi Fasli Sal Mandal (Zoroastrian seasonal-year society) which celebrated Noruz on the day of Spring Equinox. Every four years a day called Avardad-sal-gah was added to the last month, Mah Spendamad. This move was expected to bring a unification in the community and revert the rift between the Shenshais and Qadimis. Ironically, it led to the formation of a new group which came to be known as the Faslis, who followed the Calendar of the seasons. Thus, the Zoroastrians have three Calendars, Shenshai, Qadimi and Fasli. However, the Fasli Calendar is the only Zoroastrian Calendar by which Noruz and the feasts of Gahambars are retained in synchronization with the seasons and the solar year.
In Iran a group of prominent Zoroastrians were favourably impressed with the Fasli movement and they launched a campaign in 1930 to persuade the Iranian Zoroastrians to adopt the fixed Calendar of the seasons. They strengthened their case by calling it Bastani, meaning ancient. About the same time Reza Shah Pahlavi, the then monarch of Iran, adopted a National Calendar which began on the day of the Vernal Equinox. He also chose Zoroastrian names for the months of his Calendar. The majority of Zoroastrians in Iran adopted the fixed seasonal Calendar however, in Yazd, the Yazdi community resisted and to this day follow the Qadimi Calendar.
On Noruz day, Rapithaven, the Yazata of Noon, is believed to re-emerge from the earth in order that life may re-surge with the advent of Spring. We celebrate this event by performing a Jashan in honour of this Yazata. From Noruz (Roz Hormuzd, Mah Fravadin), the Rapithaven Gah (noon to 3 p.m.) is recited until Roz Hormuzd, Mah Ava, when Rapithavan goes back into the earth. It is believed that for the next five months he protects the roots of all vegetation until his re-emergence at Noruz. During his absence the recitation of the Rapithaven Gah is discontinued and instead an additional Havan Gah, is recited.
On the first day of Spring in 1992, i.e. on Mar. 21, 1992, Roz Hormazd of all three Calendars overlapped. That day initiated Mah Ava, Adar and Fravardin of the Shenshai, Qadimi and Fasli Calendars respectively. This overlap of the first Roz occurs only once every 120 years. Many zoroastrian organizations, such as Fezana, proposed a unification of all three Calendars and suggested that zoroastrians all over the world should follow only the Fasli Calendar. In response to this many zoroastrians have adopted the Fasli Calendar which is in harmony with the seasons. The Kankash-e-Mobedan (Council of Iranian Mobeds) has also agreed to follow the Fasli Calendar. However, there are some mobeds from India who feel that if they changed their Calendar then they would be disloyal to the Agiary or Atash Behram where they were ordained, while others have raised the issue that the "alaats" (religious implements) used in the ceremonies in the Adarans and Atash Behrams would require re-consecration at very high expense. Whatever the reasons may be, the Calendar changes cannot be imposed on anyone for Zarathushtra in the Ahunavaiti Gatha (Yasna 30.2) says, "Each person has his or her choice to select according to his or her own unbiased illumined mind."