From Venice to Rio, carnivals are a time honoured tradition to celebrate the end of winter with a riot of noise and dance, with masks and a temporary subversion of established social roles. The Bulgarian version is the kukeri dances.

The kukeri gambol all over Bulgaria, but it is impossible to apply to them a singular appearance, behaviour or indeed a term. Even what they are called and the times when they roam village streets vary significantly across the country, but can generally be divided into two large regions. In western Bulgaria, the kukeri dance around Christmas and New Year's Eve. They are called survakari or babugeri, and they wear spectacular headpieces made of animal hide, horns, and hens' wings with the feathers still on. In eastern Bulgaria, these masks are made of colourful rags and sequins combined to depict nightmarish faces. In this region, kukeri usually put up their act before Lent.

Traditionally, in both western and eastern Bulgaria, only unmarried men could be kukeri; the exceptions were the performers of the two leading roles in the carnival pantomime – the chief Kuker (with a capital K) and the King. These were played by married men, preferably pillars of the local community. Large cow-bells hanging on the belts of the rank-and-file mummers were also a must. Their sound, created by the rhythmic dance of dozens of men, was supposed to chase away evil spirits. The third common denominator was the lewdness of kukeri dances. When the masked troupe stormed into the village, the mummers would chase women in the streets and try to grope them. The chief Kuker would wave a long, phallic sabre painted red and engage in a raunchy pantomime with his "wife," a rag-doll baby would be born of this activity. The only masked person to show some dignity during this maelstrom would be the King, until the moment when he would symbolically plough and sow seeds in the village centre.

The idea behind these antics was more complex than appeared at first sight. On the one hand, the kukeri games were just like other carnivals – an event that upset the established social order and allowed traditional communities to let off steam – from sexual to social and political. This was why a kukeri troupe would include mock priests, tax officials, judges, soldiers, barbers and so on. It was a microcosm of society at the time. The mummers' dances were also a pagan tradition designed to ensure the end of winter and the rebirth of nature, a ritual that was supposed to bring fecundity to farms, domestic animals and people alike. The kukeri dances were also an initiation ritual, a coming-of-age activity for young men before they get married. Many historians believe that the tradition was a later reincarnation of Thracian fertility rituals dedicated to Dionysus.

But, you might ask, why the past tense in the previous two paragraphs? You surely have heard about kukeri festivals in Bulgaria, such as the Surva in Pernik in January, and the Kukerlandia in Yambol in February or March. You have probably seen a couple of kukeri dancing as entertainment at modern weddings. And you have probably watched the recent New Yorker video that shows kukeri as a living tradition in small-town Bulgaria, an act of cultural defiance against globalisation in which even young children and women participate.

The truth is that latterday kukeri are a far cry from their forebears who used to roam village streets a century ago. Today, you see Bulgarian mummers during folklore festivals, dancing and ringing their cowbells in the vast squares of big cities, or in the highly stylised videos produced by modern media. In the past, kukeri were a rural and extremely local tradition: mummers' masks and names would vary significantly even across relatively small areas. The costumes and masks were less elaborate and spectacular than their current reincarnations, which are designed purely to impress festival audiences and social media users.

In the past, the kukeri were a part of village life, not a spectacle.

The genuine tradition effectively ended in the 1950s and the 1960s, when rapidly industrialising Communist Bulgaria sucked the life out of villages, enticing their young people to the cities with the prospect of jobs in developing industries. In the first decades of its existence, the Communist regime did not tolerate "dark and superstitious" traditions, such as kukeri and nestinari dances. Yet, in some places the tradition remained, albeit on the edge of oblivion.

It was saved, sort of, in the 1960s, when Communist Bulgaria became more nationalistic and interested again in its old traditions. This, however, did not mean that it was interested in authentic traditions. Anything perceived as too risqué or "backward" was censored, and redrawn to meet the new understanding of old traditions as dignified, solemn and deadly serious. The rowdy kukeri games were tamed, especially during organised folklore festivals. The mummers dancing with their heavy masks and cowbells were also reinterpreted as a unique symbol of Bulgarian-ness.

After the collapse of Communism, the kukeri's connection to nationalism grew stronger, and they were perceived as a vibrant manifestation of the "true" Bulgarian spirit in the cold, sterile globalised world Bulgarians found themselves in. Many villages revived the tradition but more as a performance for festivals or on demand, rather than as a centuries-old spring rite that brought well-being to the communities. The masks grew larger, more elaborate and more expensive to make. Women and children joined troupes, too, changing the essence of the kukeri dances from their erstwhile male-only ritual. Curiously, this change is accepted by both nationalists, who see it as more Bulgarians, regardless of their age or sex, returning to their roots, and feminists who perceive it as gender equality gaining new grounds in traditionalist Bulgaria.

Whether you agree with these changes or not, it is hard to argue with the fact that watching kukeri dances is still a mesmerising experience that will leave your ears buzzing with the dings and dongs of cowbells for hours afterwards.