TEHRAN, Iran -- Followers of Iran's minority Zoroastrian religion gathered after sunset to mark Sadeh – an ancient mid-winter feast dating to Iran's pre-Islamic past that is also drawing new interest from Muslims.

Zoroastrian priests, dressed in white to symbolize purity, recited verses from Avesta, the holy Zoroastrian book, before more than 2,000 people on Tuesday.

Men and women in traditional dress carried torches and lit a huge bonfire on the outskirts of Tehran Tuesday, as young people danced.

Sadeh, the feast of creation of fire, has been observed since ancient days, when Zoroastrianism was the dominant religion in the powerful Persian empire.

Zoroastrianism lost dominance after Muslim Arabs invaded and conquered Persia in the seventh century. Today, most of Iran's 75 million people are Shiite Muslims, and the ruling establishment is led by clerics who preach a strict version of Islam.

After the 1979 revolution brought in the hard-line Islamic religious government, many Zoroastrians emigrated to the U.S., and their festivals were strongly discouraged.

About 20,000 Zoroastrians remain today – down from 300,000 in the 1970s, when many emigrated to the United States. They make up part of Iran's small non-Muslim population, including 150,000 Christians and 15,000 Jews.

Although the feast of fire has traditionally been marked by Zoroastrians, many Muslim Iranians joined the festival Tuesday.

"This festival promotes friendship and happiness. The feast is an opportunity to thank God for the creation of fire. The light and warmth of fire brings affection among communities. That's the reason we are here," Zoroastrian priest Sohrab Hengami said.

Ali Doosti, an Iranian Muslim who attended Tuesday's celebration, said Sadeh should not been seen from a purely religious perspective.

"Sadeh is an ancient celebration that symbolizes Iran's rich cultural heritage. There is no reason why Iranian Muslims shouldn't observe the event," he said.

To Zoroastrians, fire represents life and the inherent nature of Ahura Mazda – total goodness.

"Sadeh is a celebration of fire, but we are not fire worshippers. We worship one God," said Ardeshir Khorshidian, another priest.

Fire plays a central role in worship as a symbol of truth and the spirit of God. Prayer is often performed in front of a fire, and consecrated fires are kept perpetually burning in major temples.

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  • Iranian Zoroastrian youth carry torches to set fire on an already prepared pile of wood, during the Sadeh festival, an ancient Zoroastrians' feast celebrating the creation of fire, outside the capital of Tehran, Iran, Tuesday, Jan. 29, 2013. Followers of Iran's minority Zoroastrian religion gathered after sunset to mark Sadeh _ an ancient mid-winter feast dating to Iran's pre-Islamic past that is also drawing new interest from Muslims. (AP Photo/Vahid Salemi)

  • Iranian Zoroastrian youth carry torches to set fire on an already prepared pile of wood, during the Sadeh festival, an ancient Zoroastrians' feast celebrating the creation of fire, outside the capital of Tehran, Iran, Tuesday, Jan. 29, 2013. Followers of Iran's minority Zoroastrian religion gathered after sunset to mark Sadeh, an ancient mid-winter feast dating to Iran's pre-Islamic past that is also drawing new interest from Muslims. (AP Photo/Vahid Salemi)

  • An Iranian Zoroastrian priest sets fire to an already prepared pile of wood, in the Sadeh festival, an ancient Zoroastrians' feast celebrating the creation of fire, outside the capital of Tehran, Iran, Tuesday, Jan. 29, 2013. Followers of Iran's minority Zoroastrian religion gathered after sunset to mark Sadeh, an ancient mid-winter feast dating to Iran's pre-Islamic past that is also drawing new interest from Muslims. (AP Photo/Vahid Salemi)

  • Two Iranian Muslims watch the giant bonfire, as one of them take picture, set in a Zoroastrians' festival to mark Sadeh, an ancient feast celebrating the creation of fire, outside the capital of Tehran, Iran, Tuesday, Jan. 29, 2013. Followers of Iran's minority Zoroastrian religion gathered after sunset to mark Sadeh, an ancient mid-winter feast dating to Iran's pre-Islamic past that is also drawing new interest from Muslims. (AP Photo/Vahid Salemi)

  • An Iranian Zoroastrian priest sets fire to an already prepared pile of wood, in the Sadeh festival, an ancient Zoroastrians' feast celebrating the creation of fire, outside the capital of Tehran, Iran, Tuesday, Jan. 29, 2013. Followers of Iran's minority Zoroastrian religion gathered after sunset to mark Sadeh, an ancient mid-winter feast dating to Iran's pre-Islamic past that is also drawing new interest from Muslims. (AP Photo/Vahid Salemi)

  • An Iranian Zoroastrian girl, plays Daf, a large-sized tambourine, during Sadeh festival, an ancient Zoroastrians' feast celebrating the creation of fire, outside the capital of Tehran, Iran, Tuesday, Jan. 29, 2013. Followers of Iran's minority Zoroastrian religion gathered after sunset to mark Sadeh, an ancient mid-winter feast dating to Iran's pre-Islamic past that is also drawing new interest from Muslims. (AP Photo/Vahid Salemi)

  • Iranian Zoroastrian priests, Moubad Rashin Jahangir and Moubad Henghami (L) set firewood ablaze in celebration of the annual Zoroastrian Sadeh festival in a western suburb of Tehran on January 29, 2013. Sadeh, is an ancient Persian festival that is celebrated by setting a huge bonfire to honor fire and to defeat the forces of darkness, frost and cold. Sadeh means "hundred" and refers to 100 days and nights past the end of summer. (BEHROUZ MEHRI/AFP/Getty Images)

  • Iranian Zoroastrian youth set fire to an already prepared pile of wood, in the Sadeh festival, an ancient Zoroastrians' feast celebrating the creation of fire, outside the capital of Tehran, Iran, Tuesday, Jan. 29, 2013. Followers of Iran's minority Zoroastrian religion gathered after sunset to mark Sadeh, an ancient mid-winter feast dating to Iran's pre-Islamic past that is also drawing new interest from Muslims. (AP Photo/Vahid Salemi)

  • Spectators watch the bonfire, set in a Zoroastrians' festival to mark Sadeh, an ancient feast celebrating the creation of fire, outside the capital of Tehran, Iran, Tuesday, Jan. 29, 2013. Followers of Iran's minority Zoroastrian religion gathered after sunset to mark Sadeh, an ancient mid-winter feast dating to Iran's pre-Islamic past that is also drawing new interest from Muslims. (AP Photo/Vahid Salemi)

  • Iranians celebrate around a giant bonfire during the Sadeh festival, an ancient Zoroastrians' feast celebrating the creation of fire, outside the capital of Tehran, Iran, Tuesday, Jan. 29, 2013. Followers of Iran's minority Zoroastrian religion gathered after sunset to mark Sadeh, an ancient mid-winter feast dating to Iran's pre-Islamic past that is also drawing new interest from Muslims. (AP Photo/Vahid Salemi)

  • Iranian Zoroastrians gather to celebrate the annual Zoroastrian Sadeh festival in the western suburb of Tehran on January 29, 2013. Sadeh, is an ancient Persian festival that is celebrated by setting a huge bonfire to honor fire and to defeat the forces of darkness, frost and cold. Sadeh means "hundred" and refers to 100 days and nights past the end of summer. (BEHROUZ MEHRI/AFP/Getty Images)

  • Iranian Zoroastrian boys watch bonfire during the annual Zoroastrian Sadeh festival in a suburb of Tehran on January 29, 2013. Sadeh, is an ancient Persian festival that is celebrated by setting a huge bonfire to honor fire and to defeat the forces of darkness, frost and cold. Sadeh means "hundred" and refers to 100 days and nights past the end of summer. (BEHROUZ MEHRI/AFP/Getty Images)

  • Iranian Zoroastrian priest, Moubad Rashin Jahangir, carries a vase of coal in order to set firewood ablaze during the annual Zoroastrian Sadeh festival in a suburb of Tehran on January 29, 2013. Sadeh, is an ancient Persian festival that is celebrated by setting a huge bonfire to honor fire and to defeat the forces of darkness, frost and cold. Sadeh means "hundred" and refers to 100 days and nights past the end of summer. (BEHROUZ MEHRI/AFP/Getty Images)

  • An Iranian Zoroastrian plays a flute as he leads the priests walking to set the firewoods ablaze during the annual Zoroastrian Sadeh festival in a suburb of Tehran, on January 29, 2013. Sadeh, is an ancient Persian festival that is celebrated by setting a huge bonfire to honor fire and to defeat the forces of darkness, frost and cold. Sadeh means "hundred" and refers to 100 days and nights past the end of summer. (BEHROUZ MEHRI/AFP/Getty Images)

  • Iranian Zoroastrians gather to celebrate the annual Zoroastrian Sadeh festival in the western suburb of Tehran on January 29, 2013. Sadeh, is an ancient Persian festival that is celebrated by setting a huge bonfire to honor fire and to defeat the forces of darkness, frost and cold. Sadeh means "hundred" and refers to 100 days and nights past the end of summer. (BEHROUZ MEHRI/AFP/Getty Images)

  • Iranian Zoroastrians take part in a performance as they fight with the devil during the annual Zoroastrian Sadeh festival in the western suburb of Tehran on Jan. 29, 2013. Sadeh, is an ancient Persian festival that is celebrated by setting a huge bonfire to honor fire and to defeat the forces of darkness, frost and cold. Sadeh means "hundred" and refers to 100 days and nights past the end of summer. (BEHROUZ MEHRI/AFP/Getty Images)

  • An Iranian Zoroastrian woman reads a poem as a portrait of Iranian Prophet Zarathustra is seen on the wall during the annual Zoroastrian Sadeh festival in a suburb of Tehran on January 29, 2013. Sadeh, is an ancient Persian festival that is celebrated by setting a huge bonfire to honor fire and to defeat the forces of darkness, frost and cold. Sadeh means "hundred" and refers to 100 days and nights past the end of summer. (BEHROUZ MEHRI/AFP/Getty Images)

  • An Iranian Zoroastrian priest sets firewood ablaze in celebration of the annual Zoroastrian Sadeh festival in a western suburb of Tehran on January 29, 2013. Sadeh, is an ancient Persian festival that is celebrated by setting a huge bonfire to honor fire and to defeat the forces of darkness, frost and cold. Sadeh means "hundred" and refers to 100 days and nights past the end of summer. (BEHROUZ MEHRI/AFP/Getty Images)

  • An Iranian Zoroastrian watches a performance during the annual Zoroastrian Sadeh festival in the western suburb of Tehran on January 29, 2013. Sadeh, is an ancient Persian festival that is celebrated by setting a huge bonfire to honor fire and to defeat the forces of darkness, frost and cold. Sadeh means "hundred" and refers to 100 days and nights past the end of summer. (BEHROUZ MEHRI/AFP/Getty Images)

  • Iranian Zoroastrians gather around a huge bonfire during the annual Zoroastrian Sadeh festival in a western suburb of Tehran on January 29, 2013. Sadeh, is an ancient Persian festival that is celebrated by setting a huge bonfire to honor fire and to defeat the forces of darkness, frost and cold. Sadeh means "hundred" and refers to 100 days and nights past the end of summer. (BEHROUZ MEHRI/AFP/Getty Images)

  • Iranian Zoroastrians gather around a huge bonfire during the annual Zoroastrian Sadeh festival in a suburb of Tehran on January 29, 2013. Sadeh, is an ancient Persian festival that is celebrated by setting a huge bonfire to honor fire and to defeat the forces of darkness, frost and cold. Sadeh means "hundred" and refers to 100 days and nights past the end of summer. (BEHROUZ MEHRI/AFP/Getty Images)

  • Iranian Zoroastrian priests set firewood ablaze in celebration of the annual Zoroastrian Sadeh festival in a western suburb of Tehran on January 29, 2013. Sadeh, is an ancient Persian festival that is celebrated by setting a huge bonfire to honor fire and to defeat the forces of darkness, frost and cold. Sadeh means "hundred" and refers to 100 days and nights past the end of summer. (BEHROUZ MEHRI/AFP/Getty Images)

  • An Iranian Zoroastrian woman set firewood ablaze in celebration of the annual Zoroastrian Sadeh festival in a western suburb of Tehran on January 29, 2013. Sadeh, is an ancient Persian festival that is celebrated by setting a huge bonfire to honor fire and to defeat the forces of darkness, frost and cold. Sadeh means "hundred" and refers to 100 days and nights past the end of summer. (BEHROUZ MEHRI/AFP/Getty Images)