Hayagriva holds particular importance within the Nyingma school, the oldest of the four main lineages of Tibetan Buddhism, where a substantial body of Hayagriva practice is transmitted through the terma tradition, a distinctive Nyingma institution in which texts and instructions are said to have been deliberately concealed, in physical locations, in the minds of future disciples, or in visionary states, by the eighth century tantric master Padmasambhava and his close circle, for later discovery by qualified treasure-revealers, or tertons, at times and in circumstances judged appropriate for their transmission to a wider community of practitioners.
A number of important Hayagriva cycles are counted among these revealed treasures, understood by the tradition not as new compositions but as teachings given by Padmasambhava specifically for revelation at a later, predetermined moment, a framework that gives Nyingma Hayagriva practice a distinctive historical self-understanding quite different from lineages transmitted through unbroken, continuous teacher-to-student instruction alone. This terma system as a whole has been the subject of extensive study by scholars of Tibetan religion, who generally treat it as a genuine and historically significant institution for generating and authorizing new religious material within a tradition that also valued the authority of properly transmitted ancient teaching. Hayagriva's substantial place within this body of revealed literature reflects his standing as one of the most important wrathful protector and meditational deities specifically cultivated within Nyingma monastic and lay practice, alongside his role, shared with other lineages, as a protector associated with Avalokiteshvara more generally.