By the early 1860s, the British and Russian Empires simultaneously attempted to spread their influence into Tibet, a region which was at the time still tenuously under the control of the fading Qing Empire in China. Tibetan leadership, in an attempt to forestall culture erosion and retain its connections with the Chinese, closed its borders to Europeans of all sorts on penalty of death. Captain Thomas G. Montgomerie of the Royal Engineers, tasked with the exploration and mapping of Tibet, developed a plan to use trained natives to surreptitiously take the measurements for which British agents, regardless of their talent or preparation, would be much more vulnerable to discovery. After being asked for recommendations of loyal and talented locals who could be taught techniques in infiltration and surveying, British Education Officer Edmund Smyth suggested to Montgomerie a 33-year-old local schoolteacher named Nain Singh.
For eight years in the early 20th century, a particularly powerful and elusive man-eating leopard haunted the northern Indian village of Rudraprayag at the base of the Himalayas. It developed a taste for humans after eating corpses during the 1918 flu outbreak, in which sheer volume prevented the tradition of cremation from disposing of every dead body; once the disease subsided and the animal could no longer find dead bodies, it took to live humans instead. The leopard found the area around Rudraprayag, with a population of roughly 50,000 people and its position on a major pilgrimage route through the mountains. In a period of almost eight years from its first attack on June 9, 1918 until its last on April 14, 1926, it officially killed roughly 125 people, though the actual number was probably much higher. News of the attacks and the ensuing panic spread as far as London.