Darkar Terdzong was originally a sacred mountain where there is a big cave of Guru Rinpo Che. As a history goes, Some evila spirits escaped from Tso Ngonpo and admitted in Darkar Terdzong and they did many evil deeds. By the time, Guru Rinpo Che transformed into a man with a monkey head and took meditation in the cave. When he completed the meditation, miraculasly hit his Vajra to the roof of the cave and made a hole. He got out of the cave through the hole and defeated those evil spirits and since then it became a very sacred cave and mountain. Darkar Terdzong means a man with a monkey head. After that in around 15th Century, Tsongkapa also came to the site and used to give teachings there. We could see a big rock throne of Tsongkap while we are doing outer Kora. There are a no of sacred caves around the outer Kora and if we visit all the caves, it will take us around 5 hrs to complete the outer Kora.