Tajikistan is a landlocked, highly mountainous country in Central Asia. Its capital is Dushanbe. Over 90% of Tajikistan is covered by mountains, with the Pamir Mountains (often called the 'Roof of the World') dominating the eastern half of the country. The Pamir Knot is a geographic hub where the Himalayas, Tian Shan, Karakoram, Kunlun, and Hindu Kush ranges meet. The Fedchenko Glacier in the Pamirs is the longest glacier in the world outside of the polar regions. Because of its rugged terrain, only about 7% of the land is arable. The country shares borders with Afghanistan, China, Kyrgyzstan, and Uzbekistan.