A Hayagriva practice discovered as a treasure teaching (gter ma) by Nyemo Terton Sangye Wangchen (snye mo ba sangs rgyas dbang chen; aka rgya gong ri pa sangs rgyas dbang chen, 12th century) and Kyergangpa Chokyi Senge (1143-1216). Lama Kyergangpa was particularly devoted to the deity Hayagriva. Accordingly, in his dream practice, he visited the pure realm of Guru Padmasambhava repeatedly and received the full transmission of the "rta mgrin gsang sgrub" or "Secret Accomplishment Hayagriva." As advised by Guru Rinpoche, he also requested these transmissions from a treasure revealer in Tibet, known as Nyemo Terton. He greatly surprised the Terton with his requests for this practice because the Terton had kept his discovery of these teachings a complete secret. Two times the Terton withheld some secret oral instructions, only to be asked specifically for them later. Thus it became apparent that Kyergangpa could only have been advised to ask for them by Guru Rinpoche in person. Kyergangpa spread this teaching among his students and it eventually became popular with several lineages. Though a teaching cycle of the treasure or terma tradition, most commonly associated with the Nyingma tradition of Tibetan Buddhism, it became popular predominantly with the Sarma schools. This Hayagriva cycle of teachings continues to be practiced among Shangpa Kagyu practitioners to the present day, mainly in conjunction with the rituals of the Six-armed Mahakala, and is also very popular among various lineages of Gelugpa practitioners. The 3rd Tukwan, Lobzang Chokyi Nyima (thu'u bkwan blo bzang chos kyi nyi ma, 1737-1802), the great master of Gonlung Jampa Ling and 35th throne holder of the famous Kumbum monastery in Amdo in northeastern Tibet, wrote particularly many arrangements for this practice. [TSD]