At first sight, it looked like a typical party in a nightclub. It was mid-March in central Kyiv and a hundred or so people were wiggling on the dance floor of V’YAVA, one of the Ukrainian capital’s most popular live music venues. The hall was dark, lit only by bright blue and red spotlights. Bartenders were busy pouring gin and tonics.

But the lineup that night, in a concert hall that typically hosts pop artists and rappers, was unexpected: four Ukrainian folk singers, filling the room with their high-pitched voices and polyphonic choruses, accompanied by a D.J. spinning techno beats — all to a cheering crowd.

These days, Ukrainian folk music “is becoming something cool,” said Stepan Andrushchenko, one of the singers from Shchuka Ryba, the band onstage that night. “A very cool thing.”

More than two years into Russia’s full-scale invasion of Ukraine, folk music is enjoying a surge of popularity in the war-torn nation. Faced with Moscow’s efforts to erase Ukrainian culture, people have embraced traditional songs as a way to reconnect with their past and affirm their identity.

“It’s like a defensive measure,” said Viktor Perfetsky, 22, who started traditional singing classes after the war broke out. “If we don’t know who we are, the Russians will come and force us to be what they want us to be.”

That is a stark change of attitude in Ukraine, where folk songs had long been dismissed as archaic relics of peasant culture. Today, those same songs are being played at open-air festivals and in trendy bars. Classes in “white voice” singing, a traditional Ukrainian vocal style akin to controlled yelling, are selling out, and youngsters practice traditional dances in the streets of Kyiv, with cans of beer in their hands.

Bands like Shchuka Ryba are building on that trend to bring folk songs into the 21st century. They have collaborated with D.J.s and jazz bands to give the music a modern twist, adding electronic overtones and guitar melodies. Their ultimate goal: to reshape Ukraine’s identity around its rich but long-ignored past.

“It shouldn’t be a passing trend,” Yarina Sizyk, 27, a Shchuka Ryba singer with a distinctive, strident voice, said in a recent interview. “It should be part of everyday life.”

Folk music has been hummed in Ukraine for centuries, but they were long stereotyped as backward. In Soviet times, some folk songs were taught in schools, performed by ensembles and generally used for propaganda, but the authorities ended up turning them into a poor imitation of folk peasant culture, experts say.

After Ukraine gained independence in 1991, some groups traveled across the country to try and salvage that heritage. Kateryna Kapra, a co-founder of the cultural organization Rys, said she toured villages in central and eastern Ukraine in the mid-2010s to record and preserve authentic folk songs.

But back in Kyiv, Kapra struggled to elicit interest from urban residents. She recalled trying to organize workshops to teach traditional carols: “It was so difficult to find just 10 people in such a big city.”

Many Ukrainians were skeptical of folk music, fearing that it played into “Kremlin stereotypes about how Ukrainians are just singing peasants,” said Maria Sonevytsky, a Ukrainian American ethnomusicologist and the author of “Wild Music: Sound and Sovereignty in Ukraine.”

All that changed after Russia invaded on Feb. 24, 2022. As Moscow targeted Ukraine’s cultural heritage, including by bombing and looting museums, the songs became a marker of the Ukrainian identity.

“People realized that it’s more important than ever to preserve this culture, because it could be destroyed at any moment,” said Andrii Solomiichuk, 33, who was listening to a folk music performance in the gardens of Kyiv’s Cathedral of Saint Sophia on a recent Sunday afternoon.

Around him, small groups of folk singers dressed in traditional embroidered shirts were seated on the grass, rehearsing as they readied to take the stage. Many in the audience said they had started to listen to folk music only after the war began, drawn by a desire to reclaim their roots. “Traditions are the foundation, the lifeblood of the nation,” said Iryna Bilonizhka, 34.

As the war drags on, singing classes run by Rys have filled up. Kapra said tickets for a summer school last year “sold out in a day.”

At a recent class in Kyiv, six men stood in a semicircle and puffed out their chests as they ran through some vocal exercises. “Ta-te-ti-to-tu-to-ti-te-ta,” they sang, rising a note with each repetition and filling the room with their deep voices.

It felt like an oasis of peace in the middle of the war-battered city, but signs of the fighting were not far away. One student had a prosthetic leg — it was amputated after stepping on a mine at the front last year — while another wore a T-shirt evoking Ukrainian airstrikes on Russian targets.

Stanislav Ivko, the student who lost his leg, said he enjoyed learning about Ukraine’s history through the songs. One of his favorite ballads, “Hey, I Had a Horse,” recounts the hardships of the Cossacks, horsemen who once ruled over Ukraine’s southern regions, and their longing for better times.

Sonevytsky, the ethnomusicologist, said the songs were “a way of showing a kind of historical presence” for Ukraine and a means of countering the Kremlin’s claim that Ukraine’s nationhood is a fiction by recovering “something that was lost during the Soviet period.”

That return to the roots, however, doesn’t preclude a modern touch.

After the war began, the band Shchuka Ryba started collaborating with Fusion Jams, a Kyiv-based community of musicians, to blend traditional tunes with elements of more mainstream music like jazz, rock and electro. Their goal was spreading folk songs as widely as possible.

“We’re trying to make them accessible to a young audience,” Sizyk said on a recent afternoon. “It’s not just for grandmas and grandpas.”

She and other Shchuka Ryba members had just finished rehearsing their most popular track, “Oh, My Father Had a Daughter,” with a bassist, drummer and pianist in a studio in central Kyiv. The track is based on a folk song recorded several years ago among villagers in central Ukraine, to which the band added drums and synths.

Andrushchenko said the band wanted folk music to “become a part of someone’s life” so it has “a deeper sense than just trends.” Its members make a point, for example, of teaching spectators about traditional dances during their concerts — pausing the music to arrange them in rows and showing them the basics.

This has led to some unusual scenes in some of the Ukrainian capital’s trendiest venues. At the V’YAVA concert hall in mid-March, the band led the crowd into a kind of circle dance, with people holding hands as they spun around the room, as the bartenders looked on, surprised.

Perfetsky, who joined singing classes at the start of the war and now runs his own weekly singing sessions in a cafe, said Shchuka Ryba had inspired many to embrace folk music. “People now think, ‘Wow, they’re so cool,” he said. “And people are like, ‘I want to sing too!’”