The Treasury of Lives

Nub Lotsāwa Yonten Drak (snubs lo tsA ba yon tan grags) was born into the Nub (snubs) clan some time in the late twelfth century. He became a monk and entered Takpu Monastery (stag phu'i chos sde) and later became a translator. He is said to have received, from multiple translators, all the tantric transmissions that were available in Tibet at the time.

While Yonten Drak was teachings at Takpu some students of Jikten Gonpo Rinchen Pel ('jig rten mgon po rin chen dpal, 1143-1217), the founder of Drigung Til Monastery ('bri gung mthil), came to study the tantras with him. He later went to meet Jikten Gonpo and became his disciple.

Because of the prodigious amount of transmissions Yonten Drak had already received, it is said that whenever Jikten Gonpo gave teachings he asked Yonten Drak to give preliminary empowerments to prepare students for the main teachings. For this reason Nub Lotsāwa Yonten Drak was known as Chogowa (chos sgo ba), or "Dharma-gate Opener."

After his death, his descendants continued to perform this role, until at some point his incarnation line, known as the Chogo Tulku (chos sgo sprul sku) took over this task.