Contrary to popular belief, Halloween’s origins aren’t devilish. In fact, historians trace its roots back to an ancient Celtic festival called Samhain, celebrated around 2000 years ago. Here are six pieces of trivia about the ancient holiday.

1. SAMHAIN WAS AN ANNUAL HARVEST FESTIVAL.

Samhain was one of four major Celtic seasonal festivals, along with Imbolc, Beltane, and Lughnasadh, which occurred around 2000 years ago in regions including modern-day Ireland, Scotland, Wales, England, northern France, and the Isle of Man. Held from sundown on October 31 through November 1 (at least by today’s modern calendar), it took place between the autumn equinox and the winter solstice. Fittingly, linguists translate the Gaelic word Samhain—which was likely pronounced SAH-wen—to mean “summer’s end.”

2. WE DON'T KNOW MUCH ABOUT HOW SAMHAIN WAS CELEBRATED.

During Samhain, the Celts harvested their crops and probably slaughtered livestock for food. Then, they celebrated their abundance with sporting games and a giant—and raucous—feast. The people also prepared winter housing for itinerant warriors and shamans.

On a spiritual level, Samhain marked the time of the year in which the barrier between the earthly world and the spirit world dissolved, allowing spirits and faeries to walk among—and perhaps torment—mortals. It’s also described in countless myths and folktales as a period of mystical intensity. Celtic priests built huge bonfires, practiced divination rituals, and conducted rites to keep ghouls at bay—but since they didn’t keep written records, many of these practices remain shrouded in mystery.

3. SAMHAIN WAS TRANSFORMED INTO A CHRISTIAN HOLIDAY.

By the 7th century, many Western European nations had converted to Christianity. The Romans had celebrated Lemuria, a festival of the dead, each May—but now, the feast was dedicated to Catholic saints. During the 8th century, Pope Gregory III moved the annual festival (which was an early predecessor to All Saints' Day) for Romans to November 1—right around the time Samhain took place—and then Pope Gregory IV made the change for the Western Church. To this day, historians don’t quite know whether or not the switch was made to transform Samhain into a Christian holiday or whether it was simply more practical for the feast to be held during autumn, when harvest crops could be used to feed hungry pilgrims traveling to Rome.

Later, November 2 was designated as All Souls' Day, and the eve before All Saints' Day—once known as All Hallows' Day—was dubbed All Hallows' Eve. Over the centuries, this holiday evolved into modern-day Halloween.

4. SAMHAIN DOESN'T HAVE SATANIC ORIGINS.

Throughout history, many people have believed that Samhain has dark and demonic roots. This misconception is largely due to Charles Vallancey, a British military surveyor and amateur historian who first visited Ireland in 1762 while on a surveying mission. Vallancey became fascinated with the region, and he wrote a massive, three-volume work on its history and culture. But in his opus, the clueless scholar erroneously claimed that linguists had mistranslated the word “Samhain.” Instead of meaning “summer’s end,” Vallancey argued it actually referred to a Celtic god alternately named “Balsab”—bal meaning lord, and sab meaning death.

Scholars dismissed Vallancey’s claims, but his writings still perpetuated the myth that the Celts once celebrated a demonic god, Lord Samhain, with burnt human sacrifices and other barbaric rituals. Many early historians described the Celts as a bloodthirsty people who regularly engaged in ritualistic sacrifices, but it’s unclear whether there’s truth to these tales. Plus none of these accounts—nor ancient Gaelic legends—specifically mentioned sacrifices occurring during Samhain.

5. MANY SONGS, MOVIES, AND TV SHOWS REFERENCE SAMHAIN.

Even though Samhain was never a devil-worshipping holiday, plenty of popular films, musical acts, and TV shows reference it as such. In the film Halloween 2 (1981), the franchise’s protagonist, psychiatrist Dr. Loomis, and policemen discover that serial killer Michael Myers has scrawled the word "Samhain" across an elementary school blackboard in blood. Loomis says it references the "festival of Samhain”—and he mispronounces the holiday's name. Samhain is also referenced in Halloween III: Season of the Witch (1982), in which an Irish toy maker wants to return Samhain to its supposedly bloody roots by planning a mass sacrifice of children using cursed costume masks.

The list goes on: Characters in the cartoon TV series Ugly Americans—an assortment of demons, zombies, wizards, and more—observe a holiday called Samhain. And Glenn Danzig, the singer/songwriter who’s best known for founding punk band the Misfits, started a gothic metal/punk rock band called Samhain in the early 1980s after leaving the former music group.

6. SOME PEOPLE STILL CELEBRATE SAMHAIN TODAY.

Today, neo-pagans give the ancient holiday of Samhain a modern twist: Religious groups ranging from Celtic Reconstructionist Pagans to Wiccans have created their own unique ways to mark the mystical harvest festival, ranging from historic recreations of the Celts’ celebrations to rituals and rites honoring ancestors, deceased loved ones, or spirits.

Additional Sources: Halloween: From Pagan Ritual to Party Night and Trick or Treat: A History of Halloween.