According to Peter Hopkirk in The Great Game (OUP, Oxford, 1991) "The idea of using native explorers to carry out clandestine surveys of lawless regions beyond India's frontiers had arisen as a result of the Viceroy's strict ban on British officers venturing there. Because of this the Survey of India, which had the task of providing the government with maps of the entire sub-continent and the surrounding regions, found itself greatly hampered when it came to mapping northern Afghanistan, Turkestan and Tibet. Then a young officer working for the Survey, Captain Thomas Montgomerie of the Royal Engineers, hit upon the solution. Why not, he asked his superiors, send native explorers trained in secret surveying techniques into these forbidden regions? They were far less likely to be detected than a European, however good the latter's disguise. If they were unfortunate enough to be discovered moreover, it would be less politically embarrassing to the authorities than if a British officer was caught red-handed making maps in these sensitive and dangerous parts.