Last week, fans of the Minnesota Vikings American football team unveiled a new group chant to inspire their players. More than 66,800 fans clapped and shouted in unison as the tempo got faster and faster.

The Vikings’ new chant comes from another form of football—and from the descendants of actual Vikings. Fans of Iceland’s national soccer team introduced the rhythmic clapping and chanting in France during the summer’s European championship. Eerie and intimidating, it got a lot of airtime during Iceland’s exhilarating, England-humiliating run to the quarter-finals. The chant was so popular among fans at the tournament that others started to copy it.

The Vikings (of Minnesota) acknowledged their debt to Iceland, with the captain of the country’s soccer team, Aron Gunnarsson, appearing in videos to teach American fans how to do it. He also appeared at the season opener itself. Gunnarsson described seeing the Viking chant co-opted by another sport with a huge fanbase—Minnesota’s US Bank Stadium has a capacity equal to a fifth of Iceland’s total population—as “special.”

So does the chant hail back to the glory days of the Norse raiders, when Erik the Red was exiled from Iceland for murder and went on to discover new lands to pillage? Not quite. Its origins come from modern-day provincial Scotland, by way of a moronic film adaption of a comic book about war in ancient Greece.

The Scottish soccer team Motherwell’s fans have been doing a version of the chant—with a guttural “Hooh!”—for a few years now.

They were inspired, according to legend, by a scene in the film 300, the 2007 crowd-pleaser (if the crowd consists entirely of teenage boys) that depicts Leonidas—played by Scottish actor Gerard Butler—inspiring his Spartan warriors before battle, the throng roaring rhythmically in response to his speech.

Reykjavik-based soccer team Stjarnan made a European tournament run in 2014 that took them to Motherwell’s Fir Park in North Lanarkshire, bring them in contact with the “Motherwell Bois” trademark chant. “Because Motherwell fans performed the chant, Stjarnan fans took it up,” Kristinn Hallur Jonsson, treasurer of an Icelandic supporters’ group known as Tolfan, told The Guardian. ”They passed it on to Tolfan, and it was used throughout Iceland’s successful Euro 2016 qualifying campaign.”

And now, it’s in Minnesota. So there you go: The most ancient-sounding cheer in sport turns out to be, quite possibly, the first post-modern fan chant.