Desi Sangye Gyatso (1653–1705) was the sixth regent (desi) of the 5th Dalai Lama (1617–1682) in the Ganden Phodrang government. He founded the School of Medicine and Astrology called Men-Tsee-Khang on Chagpori (Iron Mountain) in 1694 and wrote the Blue Beryl (Blue Sapphire) treatise. His name is sometimes written as Sangye Gyamtso and Sans-rGyas rGya-mTsho By some erroneous accounts, Sangye Gyatso is believed to be the son of the "Great Fifth". He could not be the son of the Fifth Dalai Lama because he was born near Lhasa in September 1653, when the Dalai Lama had been absent on his trip to China for the preceding sixteen months. He ruled as regent, hiding the death of the Dalai Lama, while the infant 6th Dalai Lama was growing up, for 16 years. During this period, he oversaw the completion of the Potala Palace and warded off Chinese politicking. He is also known for harboring disdain for Tulku Dragpa Gyaltsen, although this lama died in 1656, when Sangye Gyatso was only three years old. According to Lindsay G. McCune in her thesis (2007), Desi Sangye Gyamtso refers in his Vaidurya Serpo to the Lama as the "pot-bellied official" (nang so grod lhug) and states that, following his death, he had an inauspicious rebirth. Iron Mountain or Chagpori (Tibetan) Sangye Gyatso founded the School of Medicine and Astrology called Men-Tsee-Khang on Chagpori (Iron Mountain) in 1694. The college was designed for monastic scholars who would, after learning esoteric arts of medicine and tantrism, mostly remain in the monastery, serving the public as would other monk scholars and lamas. In 1916, Khenrab Norbu, physician to the 13th Dalai Lama, sponsored the construction of a second secular college of Tibetan medicine and Astrology, the Mentsikhang. Mentsikhang was designed as a college for 'laypersons' who would, after receiving training, return to their rural areas for work as doctors and educators. An important part of Sangye Gyatso's contribution to medicine was his composition of the Blue Beryl Treatise and the preparation of a series of nearly 100 medical paintings illustrating medical theory and practice. These paintings were copied and distributed to several other monasteries. A set created in 1920 and preserved in Ulan Ude, Buryatia, was reproduced in facsimile together with a translation of the Blue Beryl Treatise and published in 1992. Six herbs Six medicinal substances were in common use in Tibet when they appeared in