By Yazd tradition, it is observed on Ashtad ruz, Azar Mah. This is the 100th ("sadeh" in Persian) day before Norooz. According to the Fasli calendar, this would place it on Dec 11.  The other day, observed by Kermani Zoroastrians, is Aban ruz, Bahman mah (hundredth day after the gahanbar of Ayathrima, held to be the beginning of winter) = January 24.

The chief preparation is the gathering of wood, and everyone in the community is expected to contribute:

People begin to gather an hour before sunset, a spot near a stream seems to be preferred.

Between Zoroastrians the lighting of the fire is properly proceeded by an Afrinagan-e Do Dahman, a ceremony of blessing for the whole community, and Atash Niyayesh (fire litany).

Although it is mentioned in the Qissa-i Sanjan, Sadeh does not seem to have much significance among modern Parsi Zoroastrians. The prolific Parsee writer Dr. J.J. Modi does makes a very brief note of it in his Religious Ceremonies and Customs of the Parsees (1922, p. 464). He gives the date as ruz Aban, mah Deh (= December 25 by Fasli reckoning!) He says the fire is to symbolize the approach of winter which necessitates the kindling of fires.

Sadeh, which means hundred, is a mid-winter feast that was celebrated with grandeur and magnificence in ancient Iran. It was a festivity to honor fire and defeat the forces of darkness -- frost and cold. Two different days were observed for its veneration. One celebration marked the hundredth day before the religious Norooz on the first day of the Farvardin, or March 21. (religious Noruz is different from the seasonal spring Norooz). The other one was the hundredth day after Ayathrima (one of the six feasts of obligation) held to be the beginning of winter. This day coincides with 10th of Bahman (January 30) in the present calendar. It is not clear why there are two Sadeh festivals and why different regions have had different dates. Many Zoroastrian holy days were and are celebrated twice; this is caused by the calendar reform in the 3rd century AD.

From Achaemenid times the Iranian calendar had 360 days instead of 365. Ardeshir the first Sassanid king reformed the calendar and five days were added. The new calendar receded slowly against the solar year, and the holy days, with their symbolism closely linked with the seasons, became gradually divorced from them. The months moved and so did the holy days, to make sure festivals were observed correctly both the old and the new dates were celebrated. The festival celebrated in Yazd is according to seasonal calendar and in a few villages it is called Hiromba. While the other Zoroastrians celebrated the Sadeh in Bahman. There was confusion earlier in the century as to when it should be celebrated, but most Zoroastrians have adopted the 10th of Bahman as the main event.

In Sassaniad times huge bon fires were set up. Priests led the Atash Niyayesh prayers specific to fire and performed rituals before it was lit at sunset. People would dance around the fires. Wine, a luxury in those days, would be served communally and like all other Zoroastrian religious ceremonies, the occasion would end with merriment and feasts. The most elaborate report of the celebration comes from the 10th century during the reign of Mardavij Zeyari, the ruler of Isfahan. With its Iranian origins, the Zeyari family did their best to keep the old traditions alive. Bon fires were set up on both sides of the Zayandeh-Rood river , the main river dividing the city. The fires were contained in specially build metal holders to maintain control. Hundreds of birds were released while carrying little fireballs to light the sky. There were fireworks, clowns, dancing and music with lavish feasts of roasted lamb, beef, chicken and other delicacies.

The tradition was virtually lost even amongst the Zoroastrians. In the Pahlavi era it was revived and adopted as a major celebration by the whole Zoroastrian community and it is becoming known and increasingly popular with non-Zoroastrian Iranians as well. With Zoroastrians, the chief preparation for Sadeh is the gathering of wood on the day before the festival. Teenage boys accompanied by a few adult males gather camel's thorn, a common desert shrub in Iran. For most it will be the first time they are away from their families. Wood is a scarce commodity in Iran and the occasion resembles a rite of passage, a noteworthy step for boys on their way to manhood.

The boys would take the wood to the shrine and on their return home -- if it is their first time -- there will be a celebration at home with friends and relatives. However this practice is becoming more difficult these days, although attempts are made to preserve it. Gathering wood, a scarce commodity, is increasingly difficult. In addition massive emigration into the cities or outside the country has significantly reduced the practice of this ritual.

Traditionally young boys (before the revolution girls had started joining the boys as well, but the practice stopped after 1979) would go door to door and ask for wood and collect whatever they could get, from a broken spade-handle to logs and broken branches. While knocking on doors they would chant simple verses like "if you give a branch, God will grant your wish, if you don't, God won't favor your wish" and similar verses. Before sunset all would gather outside the temple to torch the wood with prayers and chants remembering leaders of the faith and the deceased.

In ancient times the fires were always set near water and temples. The great fire originally meant (like winter fires lit at other occasions) to help revive the declining sun, and bring back the warmth and light of summer. It was also designed to drive off the demons of frost and cold, which turned water to ice, and thus could kill the roots of plants. For these reasons the fire was lit near and even over water and by the shrine of Mihr, who was lord both of fire and the sun. In AD 1000, Biruni described the philosophy behind the Sadeh festival very accurately.

The fire is kept burning all night. The day after, first thing in the morning, women would go to the fire and each one will carry a small portion back to their homes and new glowing fires are made from the ritually blessed fire. This is to spread the blessing of the Sadeh fire to every household in the neighborhood. Whatever that is left of the fire will be taken back to the shrine to be pilled in one container and kept at the temple. The festivities would normally go on for three days. Evenings are spent eating and giving away khairat (sharing food). Food prepared from slaughtered lamb and ash-e khairat soup are distributed amongst the less fortunate.

Today, Sadeh is mainly celebrated on 10th of Bahman. The fires are not lit outside and all activities take place inside the shrines. However many Iranians are becoming more familiar with the occasion and there are gatherings and celebrations outside Iran. Fires are lit and people surround themselves with music and dancing. The occasion for the majority of Iranians has no religious significance and no specific rituals are involved other than torching bon fires at sunset and having a merry time.

Courtesy of Circle of Ancient Iranian Studies at the School of Oriental & African Studies (SOAS), University of London