Surrounded by some of the world's highest mountain ranges, including the Himalayas to the south, Tibet has retained a sense of mystery over the centuries due to its relative isolation and inaccessibility. The "roof of the world," it is the highest region on Earth, situated at an average altitude of 13,000 feet, with seemingly endless, dramatic vistas of mountains and valleys. The indigenous Tibetans, more than a quarter of whom are still nomads, are predominantly Buddhist, guided for the past 500 years by the lineage of the Dalai Lamas, the spiritual and political leaders of the people. Tibet's autonomy is of course disputed, with China claiming a sovereignty that was solidified with its invasion and defeat of Tibet's army in 1950-51. Eight years later, in 1959, the 14th Dalai Lama fled with a group of top leaders, setting up their government-in-exile in Dharamsala, India, where it remains to this day. Tibet's central, ancient city of Lhasa has been its capital since the 7th century, and is home to the majestic Potala Palace, longtime residence of the Dalai Lamas, as well as such fantastic monasteries as Jokhang and Drepung.