Lying in the rain shadow of the Annapurna and Dhaulagiri massifs, Mustang offers a unique trekking experience that is possible even during the monsoon season. Its landscape is a breathtaking tableau of ochre cliffs, deep canyons, and arid plains. A restricted area until 1992, Upper Mustang has maintained a distinct Tibetan cultural identity, centered around the ancient walled city of Lo Manthang, with its royal palace and historic monasteries. Trekkers follow the Kali Gandaki river valley, exploring ancient gompas, mysterious man-made sky caves, and villages that seem untouched by the modern world.