Cradled in the folds of the Himalayas, Bhutan has relied on its geographic isolation to protect itself from outside cultural influences. A sparsely populated country bordered by India to the south, and Chinato the north, Bhutan has long maintained a policy of strict isolationism, both culturally and economically, with the goal of preserving its cultural heritage and independence. Only in the last decades of the 20th century were foreigners allowed to visit the country, and only then in limited numbers. In this way, Bhutan has successfully preserved many aspects of its culture, which dates directly back to the mid-17th century.Modern Bhutanese culture derives from ancient culture. This culture affected the early growth of this country. Dzongkha and Sharchop, the principal Bhutanese languages, are closely related to Tibetan, and Bhutanese monks read and write the ancient variant of the Tibetan language, known as chhokey. The Bhutanese are physically similar to the Tibetans, but history does not record when they crossed over the Himalayas and settled in the south-draining valleys of Bhutan. Both Tibetans and Bhutanese revere the tantric guru, Padmasambhava, the founder of Himalayan Buddhism in the 8th century.