The Upper Sultej region has for centuries been one of the most active cultural, political and religious regions in Tibet. Bon po scriptures describe the Upper Sutlej as the cradle of Zhang zhung civilization, where the mythical capital city of Khyung lung dngul mkhar was located. From Khyung lung valley, Bon religion would have expanded to Tibet and with the fall of the city during the Yar lung dynasty period, the kingdom of Zhang zhung was erased from the map. As the result of a combination of Bon po traditions and preliminary archaeologic field work two sites were established as candidates for the capital of the Horn-like Crown dynasty.

After the demise of the kingdom of Zhang zhung and the establishment of the Buddhist kingdoms of Western Tibet, mNga’ ris became once again a major religious and cultural center. Between mTho lding and Tirthapuri, it is still possible to find plenty of Buddhist monuments along the course of the Upper Sutlej River and its western tributaries (Ma nang, mDa’ ba, etc). Mostly due to the effects of the Cultural Revolution, all of them are in a ruinous state and only a few show very limited religious activity. Because of the territorial dispute with India, the whole area has been (and still is) kept in a state of nearly complete isolation from the outside world, which very seriously restricts the study of this region. After centuries of oblivion, Bon po activity in the region re-emerged in the mid 20th century thanks to the foundation of Gu ru gyam monastery. Although most of its chapels and temples were destroyed during the Cultural Revolution, nowadays the monastery is again active under the auspices of bsTan ‘dzin dbang grags rin po che, born in Hor in 1922.