An unclimbed mountain is a mountain peak that has not been climbed to the top. Determining which unclimbed peak is highest is often a matter of controversy. In some parts of the world, surveying and mapping are still unreliable. There are no comprehensive records of the routes of explorers, mountaineers, and local inhabitants. In some cases, even modern ascents by larger parties have been poorly documented and, with no universally recognized listing, the best that can be achieved in determining the world's highest unclimbed peaks is somewhat speculative. Most sources indicate that Gangkhar Puensum (7,570 metres, 24,840 ft) on the Bhutan–China border is the tallest mountain in the world that has not been fully summited. Gangkhar Puensum has been off limits to climbers since 1994 when Bhutan prohibited all mountaineering above 6,000 m (20,000 ft) due to spiritual/religious beliefs.[1]
Unclimbed mountains are sometimes referred to as "virgin peaks". Many virgin peaks exist because no one has had access to that mountain due to its geographic isolation or political instability. Some are off limits due to religious beliefs in that country or region which hold that a certain mountain is sacred and should remain inviolate. Of those, Mount Kailash, a mountain in the Ngari Prefecture, Tibet Autonomous Region of China, with an altitude of 6,638 m (21,778 ft) is one of the most prominent. It lies in the Kailash Range (Gangdisê Mountains) of the Transhimalaya, in the western part of the Tibetan Plateau. Mount Kailash is considered sacred in four religions: Hinduism, Buddhism, Jainism and Bon. Because of its status as a sacred mountain there are annual pilgrimages to see it, but setting foot on it is forbidden.
Additionally, since climbing tall mountains is usually a major undertaking and climbers are attracted to climbing the tallest ones, lower peaks (even if they are very formidable) simply get less attention, and instead the taller peaks are summited again, by parties following a new route, or perhaps during the winter when conditions are generally more treacherous.[1]