In its heyday (1400-1600), the kingdom of Lo dominated the Kali Gandaki River trade between India and Tibet. By the 18th century, Lo had lost control over this trade and had been incorporated into the modern Kingdom of Nepal. Isolated deep in the Himalayas, Lo's hereditary Rajas retained most of their feudal powers and the area remained closed to the outside world until 1991. In the spring of 1992, author Peter Matthiessen and photographer Tom Laird travelled deep in the secret valley of Sao Kohla, tucked high in the northernmost reaches of the Himalayas. They were the first Westerners to venture there in 30 years. From the central city of Lo Monthang, known as "Mustang", Matthiessen and Laird, with an entourage of attendants and horsemen, began an expedition across arid plateaux and through narrow river chasms to reach precariously perched monasteries. They camped among nomad herdsmen who spent nights guarding their goats from predatory snow leopards. This book reveals an unknown land where peaks five miles high cast their shadows over the deepest canyon in the world and where mountain nomads spend their lives herding their flocks across desolate slopes and through desert valleys.