Trolls, Nokks and Joik singing: the Nordic cultural artefacts that inspired Frozen 2

"We wanted to expand the world," Del Vecho tells RadioTimes.com, "so we went to different parts of Norway, we went to Finland and we went to Iceland, where that whole idea of myth and fairy tale formulated as part of that trip."

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The producer says that they weren't aware how deeply the story of Frozen - centred around 21-year-old Elsa, the Queen of fictional kingdom Arendelle who harbours latent superpowers which allow her to control the weather - was rooted in mythological history until after it had come out. The classic mythical trajectory isn't quite Disney-friendly, however...

In the first film, Elsa brings about an impromptu winter, covering her kingdom in ice when she discovers Anna is to marry Hans, a stranger with devious intentions, and flees her home, building a fortress of solitude.

"The mythic journey Elsa was going on, she would have been dragged down from the ice palace and killed by Hans, the eternal winter would have raged on and everyone would have died," he says. "That would have been the classic mythic tale."

But in their story, Elsa has a classic fairy tale counterpart in her sister Anna (Kristen Bell), who, in a twist on the traditional "romantic love saves the day" ending, saves her own frozen heart by sacrificing herself to protect her sister.

"Fortunately Anna, being the fairy tale character, brought that fairy tale ending to the mythic character. And in making Frozen 2, we realised we had to maintain that, because that's who Elsa is. She does things that we fear for her and are worried for her, and part of that worry is what fascinates us with that character. And keeping the two girls distinctly different, even though they’re connected now creates a great dynamic between the two of them as well."

Their trip had a profound impact on their understanding of the region, and as a result, on the story they went on to tell.

"Just by being in that environment where all these myths and fairy tales evolved from, your imagination starts to grow and you get an appreciation for why these developed in these areas, because you can just feel it in the environment."

In Norway, the surroundings brought folklore to mind, which helped them to craft creatures and plot points.

"You’re walking through the forest and these huge boulders are just in the middle of the forest seemingly out of place. You can understand why the folklore had it that there were giant rock trolls who would throw the rocks from great distances and they would just land in the middle of the forest," he says.

"Of course now we know that it was the ice age that deposited these rocks there, but you can feel where these stories came from, hidden folk underneath the mound of the rich colours of the earth."

Trolls made it into the first film, and when we first meet them, Anna and Olaf confuse them for rocks dotted throughout the forest. They return for the second instalment, too, to provide some guidance for Elsa and her cohort.

In Iceland, they couldn't help but fixate on the four elements. "You feel very small in relative size to the power of nature, and that got us thinking about Elsa and how, although she is a very powerful human, she is dwarfed by the power of nature."

The forces of nature are prevalent in the new film, with Elsa battling the sea, the earth, the wind and, while we haven't seen it yet we have no doubt it'll come, fire.

Fans will have already spotted a mythical horse in a couple of the teasers, which emerges from the water and battles with Elsa in a raging sea.

This is a Nokk, a water spirit from Scandinavian folklore, Del Vecho says. In its original form, it would spell great danger for Elsa: the Nokk was traditionally equivalent to a siren, playing enchanting songs on a violin to lure women and children into the water to drown.

But the production team took inspiration from the story and transformed it into something that could pose a character-building challenge to our hero.

"This was the idea that if there’s a body of water, there is this mythical horse made of water that might rise up to help you cross that body of water," he says.

"If it sees truth in your heart and goodness in your heart, it will take you safely across that body of water. but if it senses you're holding something back or haven’t been truthful, or haven't led a truthful life, it will drown you instead. And that concept, although we treat it differently in the movie, the idea that a water horse being an obstacle that they have to get past was very intriguing to us."

In the latest trailer, Elsa can be seen astride the Nokk, suggesting that she manages to pass its test.

Another key feature in the evocation of Scandinavia in Frozen is the score, which, Del Vecho says, pulls from a traditional type of music known as Joik. You'll recognise it as the chant-like singing that was dotted throughout the original, and some of the promotional material for the sequel.

Joik, one of the oldest musical traditions comes from the Sámi people of Norway, Sweden, Finland and the Kola Peninsula of Russia.

According to oral traditions, Joik was given to the Sámi people by the elves and fairies of the arctic land.

"[Joik singing] resonated with us," he says. "So we worked with [south Sámi musician Frode Fjellheim] to do a version of it in Frozen. We hired Cantus, which is a group in Norway, to perform it, and that musical signature carries through the second movie as well. Part of it is a Joik, but it's combined with Scandinavian music as well, so it's sort of an amalgamation."

Joik is resurgent in 2019, at least partly thanks to Frozen, which introduced millions of people around the world to the genre. Modern acts in Norway have adapted this type of singing to r&b, pop and electronica, including Norway's entry for Eurovision 2019, a group called Keiino, who finished in 6th place.

“It’s like the joiking traditions are being revitalised. There is a growing awareness, especially among people in my generation,” Marja Mortensson, a 24-year-old South Sami joiker, told Visit Norway.

Don't ever let anyone tell you that Frozen's cultural impact starts and ends with Let It Go...

Frozen 2 is released in UK cinemas on Friday 22nd November