Bhutan, a Buddhist kingdom on the Himalayas’ eastern edge, is known for its monasteries, fortresses (or dzongs) and dramatic landscapes that range from subtropical plains to steep mountains and valleys. In the High Himalayas, peaks such as 7,326m Jomolhari are popular trekking destinations. Paro Taktsang monastery (also known as Tiger’s Nest) clings to cliffs above the forested Paro Valley. The King of Bhutan is known as the Druk Gyalpo, meaning the "Thunder Dragon King". The country's landscape ranges from lush subtropical plains in the south to the sub-alpine Himalayan mountains in the north, where there are peaks in excess of 7,000 metres (23,000 ft). The highest mountain in Bhutan is the Gangkhar Puensum, which is also a strong candidate for the highest unclimbed mountain in the world. Bhutan enjoyed strong cultural links with Tibet and was located on the Silk Road between China and the Indian subcontinent. Its territory was composed of minor warring fiefs until the early 17th century. Bhutan is located on the southern slopes of the eastern Himalayas, landlocked between the Tibet Autonomous Region to the north and the Indian states of Sikkim, West Bengal, Assam, and Arunachal Pradesh to the west and south. It lies between latitudes 26°N and 29°N, and longitudes 88°E and 93°E. The land consists mostly of steep and high mountains crisscrossed by a network of swift rivers, which form deep valleys before draining into the Indian plains. Elevation rises from 200 m (660 ft) in the southern foothills to more than 7,000 m (23,000 ft). This great geographical diversity combined with equally diverse climate conditions contributes to Bhutan's outstanding range of biodiversity and ecosystems.