exchange martenitsas, which they regard as symbols of health and longevity. The white thread represents peace and tranquility, while the red one stands for the cycles of life. Bulgarians may also refer to the holiday of 1 March as Baba Marta (), meaning Grandmother March. It preserves an ancient pagan tradition. Many legends exist regarding the birth of this custom, some of them dating back to the 7th century and the time of Khan Kubrat, the ruler of Old Great Bulgaria. Other tales relate the martenitsa to Thracian and Zoroastrian beliefs. Romania and some parts of Greece also have a similar custom. In 2017, UNESCO added the cultural practices centered around the martenitsa ritual in the UNESCO Intangible Cultural Heritage Lists. The ancient Bulgarian ritual of kukeri (), performed by costumed men, seeks to scare away evil spirits and bring good harvest and health to the community. The costumes, made of animal furs and fleeces, cover the whole of the body. A mask, adorned with horns and decoration, covers the head of each kuker, who also have bells attached to his waist. The kukeri dance, jump and shout in an attempt to banish all evil from the village. Some of the performers impersonate royalty, field-workers and craftsmen. The adornments on the costumes vary from one region to another. In 2015, the ritual was entered in the UNESCO Intangible Cultural Heritage Lists as part of the traditional Surva Folk Fest held annually in Pernik. Another characteristic custom called Nestinarstvo (), or firedancing, is found in the Strandzha region. This ancient custom involves dancing into fire or over live embers. Women dance into the fire with their bare feet without suffering any injury or pain. In 2009, the ritual was entered in the UNESCO Intangible Cultural Heritage Lists. UNESCO World Heritage Sites Bulgaria has nine UNESCO World Heritage Sites, which are part of the national route tourist map of 100 national tourist sites of the Bulgarian Tourist Union: The early medieval large rock relief Madara Rider Two Thracian tombs (one in Sveshtari and one in Kazanlak) Three monuments of medieval Bulgarian culture (the Boyana Church, the Rila Monastery and the Rock-hewn Churches of Ivanovo) Two examples of natural beauty: the Fisherman Momerioland the Sreburna Nature Reserve The ancient city of Nessebur — a unique combination of European cultural interaction, as well as, historically, one of the most important centres of seaborne trade