Gangkhar Puensum is the highest mountain in Bhutan and a strong candidate for the highest unclimbed mountain in the world with an elevation of 7,570 metres (24,836 ft). Its name means "White Peak of the Three Spiritual Brothers".

It lies on the border with Tibet (however, the exact location is still disputable). After Bhutan was opened for mountaineering in 1983 there were four expeditions that resulted in failed summit attempts in 1985 and 1986.

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. In 1999, a Japanese expedition successfully climbed Liankang Kangri, a 7,535 metres (24,721 ft) subsidiary peak (not an independent mountain), separated from the main peak by a 2 kilometres (1.2 mi) long ridge to the north-northwest. 

According to en.wikipedia