The S21 Desert Highway (also known as the S21 Altay-Urumqi Expressway) is Xinjiang's first expressway traversing the heart of a desert. It stretches approximately 342.5 kilometers from Fuhai County in Altay Prefecture in the north to Urumqi in the south. Opened to traffic at the end of 2021, it has reduced the travel time between Urumqi and Altay to about 3.5 hours. The highway runs through the Gurbantünggüt Desert, China's second largest desert, and the heart of the Junggar Basin, connecting diverse landscapes including Gobi, oases, sand dunes, yardang landforms, and lakes, earning it the reputation of "Xinjiang's most beautiful self-driving corridor." Unlike traditional barren deserts, the Gurbantünggüt Desert is a fixed or semi-fixed desert, where drought-resistant plants such as saxaul and tamarisk can be seen along the way, and wild animals such as Przewalski's horses and gazelles can be encountered, showcasing a unique sense of life.