Junast was born in Horqin Right Middle Banner county in Inner Mongolia in 1934. His father and grandfather were farmers, originally from Chaoyang in Liaoning. His father wanted him to have an education, so Junast was sent to a local private school from the age of eight, where he studied Chinese and Mongolian, including the Confucian classics. In 1951 he passed the entrance exam for the Hinggan Middle School in Ulan Hot, where he specialized in the Mongolian language, but in the autumn of the following year he was accepted into the newly established Mongolian Languages and Literature program at the Inner Mongolia Teachers College, despite having only been at high school for one year. In March 1953 he joined the Communist Party of China, and in September he was sent to study Mongolian language at Beijing University. After graduation, in 1954, he was assigned to teach at the Inner Mongolia Mongolian Specialist College. In 1954 he went back to Beijing to participate in a survey of Mongolic languages, and on completion of this work he transferred to the NationalMinority Languages Research Institute of the Chinese Academy of Social Sciences. From 1955 to 1956 he engaged in fieldwork in Qinghai, collecting materials for the study of the Monguor language. He returned to Qinghai to study the Monguor language several more times during the 1950s and 1960s. On the outbreak of the Cultural Revolution, Junast was labelled a "May 16 element", and suffered beatings and abuse. From 1969 to 1973 he was sent for re-education through labor at a Cadre School. It was during this period that Junast started to study the 'Phags-pa script. From 1977 onwards, the focus of Junast's research turned to the study of documents and monuments written in the 'Phags-pa script, with his first publication on the subject being a collection of Yuan dynasty official seals carved in the convoluted "seal script" form of the 'Phags-pa script. During the 1980s he published numerous articles on the 'Phags-pa script, culminating in a critical edition of the Yuan dynasty rhyming dictionary of Chinese in the 'Phags-pa script, Menggu Ziyun. In 1988 Junast was invited to teach in Japan, and he accepted a position as visiting professor at the Tokyo University of Foreign Studies, where he remained until the mid-2000s. In 1994 he retired from the Chinese Academy of Social Sciences, but he continued to publish articles on the 'Phags-pa script, and was engaged in research on the computerization of the 'Phags-pa script. He died in hospital in Beijing on 9 April 2010.
