However, the massif remained unclimbed until 1960. The Amne Machin mountains had been overflown by a few American pilots who overestimated the elevation to 30,000 feet (9,100 m). A 1930 article of the National Geographic estimated the peak elevation to 28,000 feet m according to the report of Joseph Rock, an American botanist and explorer who, despite death threats from the Golog Tibetans, had ventured to within 80 km of the mountain. For a while, the mountains were considered as a possible place for a peak higher than Mount Everest. While Rock only downgraded his estimate publicly in 1956 to "not much more than 21,000 feet", he did give a detailed description of the peaks: By 1980 Anyi Machen had been resurveyed at .