On November 25, Yakutia celebrates Olonkho Day, the oral folk epic of the republic, recognized as a UNESCO masterpiece of world heritage. This day honors a significant part of the Yakut spiritual culture, which was only documented in the 20th century. It is preserved and developed thanks to the Olonkho Research Institute at the North-Eastern Federal University named after M.K. Ammosov, as well as various Olonkho houses and the Olonkho Association. The epic is popular not only in Yakutia: it has been translated into ten languages (with a total of 150 works) and is performed on the stage of the Olonkho Theater, reports YSIA. On November 25, 2005, UNESCO declared the Yakut heroic folk epic a masterpiece of oral and intangible heritage of humanity. Olonkho (Yakut: Олоҥхо) is the oldest epic art of the Yakut (Sakha) people and holds a central place in Yakut folklore. The term "Olonkho" refers both to the epic tradition as a whole and to individual stories. The poems, averaging between 10,000 and 15,000 verses, are performed by folk storytellers called olonkhut. The cosmogony of Olonkho is structured according to the Ayy religion. The action takes place in three worlds: Upper World (Üöhee Doidu), Middle World (Orto Doidu), Lower World (Allaraa Doidu). At the center of the universe stands Aal Luuk Mas — the World Tree. Its roots reach into the Lower World, home to dark, hostile forces; its crown grows in the Middle World, where humans live; and its branches stretch into the sky, where the deities of the Upper World dwell. The main theme of Olonkho is the fate of the epic tribe Ayy Aimaga (Айыы аймаҕа), the ancestors of humanity, striving to establish a prosperous and happy life in the Middle World. A key feature of Olonkho as a genre is its unique historicism: it is presented as a story of human society, but in a mythological form.