Nestinarstvo or Anastenaria is an ecstatic dance in a traditional barefoot fire-walking ritual that is performed in some villages in Northern Greece and Southern Bulgaria. Those who celebrate this ritual are descendants of refugees who entered Greece after the Balkan Wars of 1911-1912 and the Turkish-Greek Population Exchange of 1923.
Every year, Bulgarian and Greek villages observe a unique ritual cycle. Although Saint Constantine and Saint Helen are at the center of this tradition, all-important days in this cycle correlate with significant days on the Greek Orthodox calendar and are named after various Christian saints. During this cycle, there are two big festivals dedicated to these two saints. Each festival lasts for three days and is characterized by procession, music, dancing, and animal sacrifice.
On the feast days of Sts. Constantine and Helena (3 and 4 June), Nestinarstvo fire-dancing is the climax of the annual Panagyr ritual in the village of Bulgari, in the Mount Strandzha region of south-east Bulgaria. In the morning, consecrated and ceremonial rituals are solemnized to ensure the well-being and fertility of the village. A procession accompanied by drums and bagpipes passes outside the village to spring with holy water, carrying sacred icons representing the two Saints. In the spring, holy water and candles are given to every participant for good health, and in the evening the festival culminates in the most awe-inspiring form of veneration of the Saints, the fire dance (firewalking), in which the participants barefoot walk over glowing coals, barefoot, while carrying icons of Saints Constantine and Helen. In silence, a circle is formed around the burning embers led by the sacred drum, and then the Nestinari, the spiritual and physical leaders through whom the saints express their will, come into the circle and begin treading the embers.
Nestinarstvo was once celebrated in as many as thirty Bulgarian and Greek villages nearby and today it is only celebrated in Bulgari, a village of just a hundred people. During the Panagyr, however, thousands of people crowd the village, with a recent increase in Greeks in attendance. Unfortunately, the ritual became commercialized in the 20th century, resulting in its performance for tourists in Bulgarian seaside resorts, performed by people who have little connection to the original tradition. Even so, the rituals are still practiced in more authentic forms in five villages in northern Greece: Ayia Eleni, Langadas, Meliki, Mavrolefke, and Kerkini; and six in Bulgaria: Balgari, Gramatikovo, Slivarovo, Kondolovo, Kosti, and Brodilovo.
References
(https://ich.unesco.org/en/RL/nestinarstvo-messages-from-the-past-the-panagyr-of-saints-constantine-and-helena-in-the-village-of-bulgari-00191) (https://en.wikipedia.org/wiki/Anastenaria)