Gesar ("ge sar") is a warrior-like king in the realm of Ling ("gling") and the protagonist of a voluminous folkloric poem that many Tibetan bards have performed for centuries. With Gesar's increasing fame in modern times, the orature has become a quintessential representation of Tibetan culture. This paper compares two children's books that draw on the Gesar tradition, "Tibetan Heroic Epic: Gesar Children's Literature Collection" ("gling ge sar sgrung gi byis pa'i rtsom rig dpe tshogs") and "Gesar Epic: Hor-Ling Battle" ("ge sar rgyal po'i sgrung hor gling gyul 'gyed"). The two books approach the relationship between adaptation and authenticity differently, with "Tibetan Heroic Epic" adhering to textual renditions of the orature, while "Gesar Epic" significantly transforms the ancient tradition. The latter is more accessible for children. As much as the editors of "Tibetan Heroic Epic" aspire to present an authentic Tibetan tradition to children, their method of literal transcription is unappealing and unsuccessful. The problem of "Tibetan Heroic Epic" mainly lies in a flawed understanding of cultural authenticity. Culture, when alive and thriving, is mobile and fluid. Hence, the authenticity of culture is not about keeping a tradition unchanged from the past to the future. With Gesar's adaptation in children's literature as an example, the author argues that cultural authenticity is not an imagined reservoir of immutability. Instead, authenticity is generated from changes made by people who know and own that particular culture.