Butön Rinchen Drub, a Sakya lama raised in a Nyingma family, was the eleventh abbot of Zhalu Monastery, from 1320 to 1356. Some enumerations list him as the first abbot, as he significantly expanded the institution. He was an important teacher of the Prajñāpāramitā and a key lineage holder of the Guhyasamāja and Kālacakra tantras as transmitted in the Geluk tradition, and the Kālacakra, Hevajra and Sampuṭa tantras as transmitted in the Sakya tradition. He is generally credited as the creator of the Tibetan Buddhist canon, the Kangyur and Tengyur, and his History of Buddhism is still widely read. In addition to his Sakya training, he also studied in the Kadam and Kagyu traditions.