Despite its notability and spectacular visibility from the old trade route between India and Lhasa that passes through the Chumbi Valley, the mountain has seen little climbing activity. It was known to climbers passing by on the way to Everest and was scouted by Odell as early as 1924. In 1937 a permission to climb the sacred mountain was granted to a British expedition headed by Freddie Spencer Chapman by both the Tibetans and the Maharajah of Bhutan. Although no refusals are known of earlier climbing requests, Chapman believed this was the reason it had gone unclimbed until 1937. Six porters accompanied the 5 man climbing team from Phari across Sur La into Bhutan. Chapman and Sherpa Pasang Dawa Lama (of the American K2 expedition fame) reached the summit via the southeast spur on 21 May 1937. The protracted and epic descent, which they were fortunate to survive, is described in detail in Chapman's Helvellyn to Himalaya published in 1940.