During the time of the 13th Dalai Lama Thupten Gyatso, Trehor Khangsar Rinpoche was the Abbot of the Tantric College of Gyumey. Among his students were high lamas such as Jampa Chodak, who held the post of the 90th Gaden Tripa. Jampa Chodak was also the student who wrote a biography of Trehor Khangsar Rinpoche.

Pabongka Dechen Nyingpo was also a student of Trehor Khangsar Rinpoche, receiving teachings and initiations that may have well been passed down to many of the most prominent Gelugpa lamas in the world today.

In fact, it was from him that Pabongka Rinpoche received the initiation of the Vajrayogini’s tantra in the tradition of Ngulchu Dharmabhadra.

Trehor Khangsar Rinpoche was born in a large town known as Ganzey located in the Eastern part of Tibet, in the Trehor region of Kham. He was also known by the name of Lobsang Tsultrim Denpay Gyaltsen. The name "Trehor" originates from Mongolia, from the time when the Mongols under the rule of Gushri Khan established themselves in the Kham region after defeating the King of Beri. As a young monk, Trehor Khangsar Rinpoche studied the Five Great Treatises at Drepung Loseling College in Lhasa and went on to become the seat holder at Ganzey Monastery. Eventually, he ascended the prestigious and respected position as abbot of Gyumey.

Among the texts written by Trehor Khangsar Rinpoche, we find notable commentaries on the First Stage of Yamantaka, Quick Path Lamrim, the Profound Path of the Six Yogas of Naropa, the Kalachakra Tantra and the Profound Guru Puja. In particular, there is also a specific series of texts on the Kalachakra written by Trehor Khangsar Rinpoche that are still being used to this day.

Trehor Khangsar Rinpoche was also known to have written rituals specifically to protectors. In the fourth volume of Trehor Kangsar Rinpoche's collected works, we find protector rituals for invoking Dorje Shugden, Setrap and Nechung oracles that were written as a "tangrang" (thanksgiving) for the deities’ activities following auspicious oracle invocations.

In the short request for activity to Dorje Shugden, the Protector is described as riding a snow lion, a description missing from earlier Gelug descriptions. The text also mentions the role of Dorje Shugden as the protector of Manjushrigarba, which is the name of Lama Tsongkhapa's incarnation in Tushita land. The short request for activity also contains a reminder to protect the Dharma and a request to protect the practitioners from illnesses, for them to have long lives and to be assisted on their path to gain attainment of realisations.

Some contemporary scholars claim that the practice of Dorje Shugden arose and was promoted predominantly by Pabongka Rinpoche. However, the discovery of texts like those written by Trehor Khangsar Rinpoche and other Lamas before him prove that the practice was very much alive and propitiated long before Pabongka Rinpoche. Later, Pabongka Rinpoche composed the kangsol to Dorje Shugden at the request of a lama of the Kham area, and not on a personal initiative. This alone denotes that Dorje Shugden's practice and rituals were already established in the region prior to the arrival of Pabongka Rinpoche, countering these scholars’ assertions. Further, Trehor Khangsar Rinpoche writings referenced the fact that oracle invocations of Dorje Shugden were very much practiced at the time, contrary to later claims that Shugden was restricted by the 13th Dalai Lama and established only by Pabongka in the mid 20th century.

The catalogue of Lobsang Tamdin lists this particular work, which also means that Dorje Shugden's practice had found its way to Mongolia. The practice was not confined only to Tibet, but by this time, there were many lamas who had also brought Shugden, as well as other Gelugpa teachings, into Mongolia where it was also flourishing.