Every year around October and November, Hindus around the world celebrate Diwali, or Deepavali—a festival of lights that stretches back more than 2,500 years. And in India, the five-day celebration marks the biggest holiday of the year.

Like many Hindu festivals, there isn’t just one reason to celebrate the five-day holiday. Pankaj Jain, a professor of anthropology, philosophy, and religion at the University of North Texas, says that the ancient celebration is linked to multiple stories in religious texts, and it’s impossible to say which came first, or how long ago Diwali started.

Many of these stories are about the triumph of good over evil. In northern India, a common tale associated with Diwali is about King Rama, one of the incarnations of the god Vishnu. When an evil king in Lanka (which some people associate with Sri Lanka) captures Rama’s wife Sita, he “builds up an army of monkeys” to rescue her, Jain says.

The monkeys “build a bridge over from India to Sri Lanka, and they invade Sri Lanka and free Sita and kill that evil king,” he says. As Rama and Sita return to the north, “millions of lights are spread out across the city Ayodhya just to help them come back home, just to welcome them.” Lighting lamps has long been one of the ways that Hindus celebrate Diwali.

A Pakistani Hindu family offers prayers and light candles as they mark Diwali, the Festival of Lights, in Lahore, 2016. (Credit: Arif Ali/AFP/Getty Images)
A Pakistani Hindu family offers prayers and light candles as they mark Diwali, the Festival of Lights, in Lahore, 2016. (Credit: Arif Ali/AFP/Getty Images)

In the south, Diwali is popularly linked to a story about the Hindu god Krishna, a different incarnation of Vishnu, in which he frees some 16,000 women from another evil king. In the western state of Gujarat, the New Year coincides with Diwali (there are multiple New Years throughout India), and Diwali is associated with asking the goddess Lakshmi for prosperity in the coming year. During the festival, many celebrants exchange gifts and coins.

Other religions like Buddhism, Jainism, and Sikhism use Diwali to mark important events in their histories, too. Professor Jain, who is petitioning one of Texas’ school districts to recognize Diwali, says that while Diwali is a religious holiday, it’s also somewhat of a national holiday in India. Comparing it to Christmas in the U.S., he points out that many non-Christians in America still buy a Christmas tree and give each other gifts.

Vasudha Narayanan, a professor of religion at the University of Florida, disagrees with this, arguing that not everyone in India celebrates Diwali. But because about 80 percent of India is Hindu—with Buddhists, Jains, and Sikhs making up two or three percent more—it’s still celebrated by the majority of the country.

Narayanan says that in the past century or so, fireworks have become a major part of the Diwali celebrations. These aren’t the large-scale fireworks that American cities deploy on the 4th of July—during Diwali, individual families all set off their own fireworks (which admittedly goes on in some parts of the U.S. too, like Washington, D.C.).

Indian women wave sparklers as they participate in a celebration for the Hindu festival Diwali on the banks of the Yamuna river in the northern city of Vrindavan, 2014. (Credit: Roberto Schmidt/AFP/Getty Images)
Indian women wave sparklers as they participate in a celebration for the Hindu festival Diwali on the banks of the Yamuna river in the northern city of Vrindavan, 2014. (Credit: Roberto Schmidt/AFP/Getty Images)

“On the night before Diwali, you hardly ever slept,” Narayanan says of the fireworks. “I mean, the sound was that loud.”

But recently, the Indian government banned the sale of fireworks during Diwali, citing environmental concerns. According to Narayanan, this has upset a lot of revelers in India. On Twitter, many have complained that Diwali without fireworks is like Christmas without a Christmas tree.

While Narayanan understands the desire to keep with tradition, she also gets the government’s concern. India’s air is already very polluted, and she says the amount of fireworks released during Diwali makes the problem worse.

“Hinduism also advocates doing good to others, and nonviolence,” she says. Therefore, she argues that traditions should be rethought if they “cause violence to someone else’s health.”