Every so often, a video goes viral showing a form of Soviet-era Russian dancing called the Berezka. These troupes of female dancers elaborate headdresses and flowing skirts seem to glide so effortlessly across the floor that many assume they are standing on hover boards, roombas, or—at the very least—roller skates. According to all the articles that come out about the troupe and the style of dancing, it was invented by a Soviet ballerina named Nadezhda Nadezhdina in the middle of the twentieth century. In the articles, which tend to quote from an interview she gave to The New York Times in the 1970s, she says that it was based on Slavic folk dances.
But a group of Karachay-Balkarian dancers, from the Caucasus mountain regions in the south of Russia, near Turkey, have a very similar style of folk dancing they call the Abezek, which is demonstrated here.
Though the headdresses and costumes on the Russian dancers and the Caucasian ones are very different, their floating movements and the giant geometric shapes and wheels they make as they perform are very similar. It is possible that the Slavic folk dances (the khorovod, which looks very little like either of these) from which the Berezka style claims its origin shares something in common with this Caucasian dance, but it seems disingenuous not to recognize that the two styles are remarkable similar.
One guess for why it was described as a Slavic dance in the 1970s might be due to Soviet cultural pressure. At the time, the largely Muslim people of the Karachay-Balkars were suffering terribly under Soviet restrictions and rule, with mass arrests and deportation making life there very difficult. Alternately, it could be an error in translation, or one the reporter made that has been repeated for decades.
The effect is achieved by the dancers moving their feet very fast under their voluminous skirts, while holding their upper bodies extremely stiff.