Jamdrak Rinpoche, biographical notes

The glorious Jamyang Drakpa was a sovereign of knowledge, compassion and capability and a great guide of all beings. He had perfected and ocean of the virtues of learning, reflection, and meditation by gathering within the glorious knot of his heart all the streams issuing forth from the nectar of the speech, the extracts of the realization of the three great tertons and vidyadharas. He was also chief among the direct disciples of the sun and moon pair of Jamgons who in accordance with the vajra prophecy accepted the oath of carrying out the activity to linking one million eight hundred thousand (beings to this teaching).

Jokyab Rinpoche, (Pema Trinley Nyingpo), Light of Wisdom, Vol. 1

"Jamyang Drakpa was a student of both Jamgons (Jamyang Khyentse Wangpo and Jamgon Kongtrul) and was present when the root text was revealed. He is one of the sixteen destined disciples who would spread the teaching and is predicted in the root text Lamrim Yeshe Nyingpo. Consequently, Jamyang Khyentse Wangpo told him "Your activity for the welfare of others is to propagate the Lamrim Yeshe Nyingpo. So do that!" The explanatory lineage for the Lamrim Yeshe Nyingpo at one point rested on him. He had reached a high age, above eighty, by the time Jokyab Rinpoche came to receive the transmission for the Lamrim. I knew Jokyab Rinpoche personally since I was fortunate enough to receive the teachings on the
Lamrim Yeshe Nyingpo from him. Jokyab Rinpoche also received the entire transmission for the Chokling Tersar from my uncle and guru Samten Gyatso Rinpoche as well as the Damngak Dzo from Kyungtrul Kargyam Rinpoche. Samten Gyatso Rinpoche sent a message to Dru Jamyang Drakpa, requesting teachings on the Lamrim Yeshe Nyingpo on behalf of Jokyab Rinpoche. Jokyab remained with the great master Jamyang Drakpa for an entire year, but the teachings on the Lamrim did not commence during the first six months, due to the master’s advanced age and fragile health. The first months were spent on questions on the Guhyagarbha Tantra with which Jamyang Drakpa was quite familiar, knew by heart and therefore didn’t have to look at pages in order to consult. The second half of the year was spent on the Lamrim.
When Jamyang Drakpa finally began the explanations, Jokyab took notes on small pieces of paper, one after the other, so that at the end he had a heap almost the size of a volume of scriptures. Having returned to Tsikey Monastery, he organized and transcribed his notes and this collection is what is now known as the Zurgyen, the Side Ornament. After this he went to Central Tibet."

Tulku Urgyen Rinpoche, Light of Wisdom, Vol. 1