Nain Singh, together with Kishen and Kalian Singh, had been attached to the second Forsyth Mission to Yarkand, which left India in 1873. For reasons beyond his control, Nain Singh had not been able to break much new ground while attached to the Mission. But when the Mission returned to Leh in the summer of 1874, Captain Trotter, who had succeeded Montgomerie on the latter's departure from India in 1873, dispatched Nain Singh by a northerly route across Tibet to Lhasa. The exploration was undertaken on the instructions of General Walker, superintendent of the GTS. It was initially intended that the Pundit should be accompanied by Kishen Singh, but Kishen was suffering from exposure, incurred on a journey from Khotan.

There is evidence that Nain Singh was worn out after nearly two decades of the rigors of traveling under difficult and dangerous circumstances. In a letter to General Walker discussing the pundit's participation in the second Forsyth Mission, Montgomerie wrote that "I do not think he was greatly taken with the idea of going Northand East of Ladak, though he would not have minded anything to the South East." Montgomerie continued: "he may make one grand push if he fully understands that it is likely to be his last, and that he will get some position given him, or a pension. He does not at all fancy having much more of actual exploration." According to Trotter, "on the return of the mission to Ladakh, being anxious to have an opportunity of gathering fresh laurels, he [Nain Singh] volunteered to proceed on a fresh exploration." This was to be his last "grand push," and he may have volunteered with the promise of a pension or other inducement, particularly since the journey involved the relatively level plains of Tibet rather than the rugged passes over the Karakorum and the Kunlun.

The objectives of this last journey were to survey a route from Leh to Lhasa by a much more northerly path than the one he had taken in 1865. From Lhasa he was to try to join the caravan to Peking, which the Survey of India had heard left from Lhasa every three years. Should this not prove possible, his instructions were to return to India by an unexplored route, either down the course of the Tsangpo Brahmaputra, or through the Himalayan kingdom of Bhutan.

This was the pundit's third clandestine penetration of Tibet. Officials on the frontier would have been on the lookout for him. He had also been in Leh on numerous prior occasions and was known to be in the service of the Indian government. Accordingly, more elaborate precautions than usual were needed in order to ensure his safe passage in disguise across the border. The frontier crossing was the key to everything. Once into Tibet, Nain Singh would be relatively safe, since he would be passing through thinly populated areas.

The deception involved a rather complex scheme in which William Johnson (famous for his visit to Khotan in 1864), now wazir of Ladakh in the service of the maharaja of Kashmir, was to conspire with the headman of the village of Tankse, near the Tibetan border. The headman was to collect a number of sheep for the Pundit, giving the impression to the Ladakhis that the sheep were to be used as baggage animals to carry the Pundit's merchandise on the road to Yarkand. This was quite plausible. The sheep were indeed to be used as baggage animals, and Tankse was on the Changchenmo route to Chinese Turkestan. The Pundit, however, was not going to Chinese Turkestan, but to Tibet.

Another problem which Trotter had to address was the question of how to provide security for the funds the Pundit would need to reach Lhasa and then continue to Peking and home to India. For the first stage of the journey, as far as Lhasa, the pundit carried sufficient cash with him. But to carry more, even inthe form of merchandise, through areas infested by robbers was to Trotter's mind to risk the life of his explorer. As it happened, the triennial Lopchak mission from Ladakh to Lhasa was about to leave Leh. Nain Singh had traveled with this caravan before, and Johnson got the Lopchak to agree to take money to Lhasa for Nain Singh, who would collect it personally when he arrived. Since the caravan was a large one and traveled along a well-known road, it was felt that this arrangement would provide ample security.

For the final section of his journey, from Peking back to Calcutta by sea, Trotter provided the Pundit with a letter of introduction to the British Minister in Peking. The minister was to arrange transportation for the Pundit once the letter was presented.

Nain Singh's parry included four attendants. One of these was his servant Chumbel, two were Tibetans who had also accompanied him in the past, and the fourth was a local man, loaned by the headman of Tankse. They set out from Leh on 15 July 1874, Nain Singh leaving behind the impression that he was returning to Yarkand.

Nine days later they reached the last village before the Tibetan border, and under cover of darkness the pundit and his companions dressed in the priests' robes which had been tailored secretly for them in Leh. At first they did follow the Changchenmo road north, but after two days turned east. Slow progress was made, the pace determined by the speed of the sheep. Crossing the "frontier" was something of an anticlimax, just one hut with a small guard, which they passed without incident. The party was now in Tibet, on the north bank of Lake Pangong, and proceeding in a generally southeast direction, parallel to the Tsangpo but at distances varying from one hundred to two hundred miles north of the course of the river. The villager from Tankse had gone ahead of them and by using his good offices had obtained from the local officials the permission needed to proceed into the heart of Tibet. The pundit continued past Lake Pangong and was able to fix the location of its eastern extremity. Godwin-Austen and others had mapped the western parts of this elongated lake, but the easternmost point, well into Tibet, had now been located for the first time.

Nain Singh's route now took him on to the great lacustrine plain of central Tibet. Most of the lakes were salt, but some were fresh water and the travelers were able to fill their waterskins, made of sheep stomachs. For the first ten days the road was not far to the north of the route taken by Kalian Singh while on his way from Rudok to the gold mines of Thok Jalung.

For security, Nain Singh had secreted his Indian rupees in a number of hiding places, the main one being in a wom pad on the back of an old donkey. This animal was dubbed the "Government Treasurer." Occasionally, they would deliberately camp well off the road, to avoid robbers whose favorite trick was to cut the tent ropes at night and plunder the camp while the sleepers were trying to extricate themselves.

The altitude was, on average, a little over fourteen thousand feet. A few shepherds were seen, but the paucity of human population was more than made up for by an abundance of animal life.

About one-third of the way between Lake Pangong and Tengri Nor, Nain Singh entered an area inhabited by Khampas, who said that they had migrated there from Kham (north and east of Lhasa) twenty-five years earlier. Accomplished horsemen and sportsmen, they tended herds of horses, sheep, and goats. They also had a bad reputation for plundering caravans. However, because one of his servants had befriended one of the Khampas in Ladakh some years before, the pundit was able to join a small group of them going in the same direction, and which afforded some protection for a while. Then, taking a devious route to minimize the risk of being robbed, they arrived in the gold-mining area of central Tibet.

The pundit's account of the mines of the Thok Daurakpa area led Trotter to downgrade the importance which had been attached to the Tibetan goldfields as a result of his earlier report of 1867. The mining area through which Nain Singh was now passing did produce gold of a higher quality than that found in look Jalung to the west. But the gold of Thok Daurakpa was embedded in rock, rather than soil, and the water for washing the pulverized rock had to be carted in skins on the backs of donkeys from a stream over a mile away. The amount of gold produced was so small that the local shepherds were wealthier than the gold diggers. Furthermore, said the Pundit, he believed that only two other mines in northern Tibet were being worked, and both were evep smaller than Thok Daurakpa.

Pausing for just one day at the gold mines, Nain Singh and his companions, now halfway to Tengfi Nor, continued across the Chang Tang. Their altitude was now sixteen thousand feet, but the sun was warm, grass grew underfoot, and herds of antelope grazed nearby On his route from Lake Pangong, the pundit had been marching parallel to a snowy range lying just to the south, a chain of mountains now known as the Nain Singh Range. The extension of this range continued up to a point south of Tengri Nor.

Nain Singh struck the northwest comer of Tengri Nor (the easternmost point of which is about eighty miles due north of Lhasa), after a journey of sixty-four marches from Noh, near Lake Pangong. He had mapped a chain of lakes across central Tibet, none of which had been seen before. Only Tengfi Nor itself had been visited before by a trans-Himalayan explorer, in 1872, when Kishen Singh made a complete tour around it.

Nain Singh followed the path of Kishen Singh along the northern shore of Tengri Nor for fifty miles and then, like his predecessor, turned to the south in the direction of Lhasa. After some ten to twenty miles, he struck off by a different and less direct route to the Tibetan capital.

The pundit and his party entered Lhasa on 18 November 1874. They had started from Leh on 15 July, averaging less than ten miles per day over the 1,095 miles from Leh to Lhasa. But the sheep purchased in Ladakh, although slow movers, had more than proved their worth. Of the twenty-six that started out on the journey, four or five covered the entire distance. Others were eaten or had been taken sick. All carried twenty to twenty-five pounds of baggage on their backs and foraged for whatever food they could get.

Nain Singh was anticipating small luxuries such as fresh vegetables, beer, and a more comfortable accommodation in Lhasa. Unfortunately, this was not to be. Just before reaching the city, he heard a rumor that the Chinese were aware that a British agent was approaching Lhasa from India. The pundit sent one of his servants ahead of him to see if the Lopchak mission had arrived with the remainder of his funds. The response was negative; in fact, the head of the mission had died on the way to Lhasa. Now Nain Singh's penury was to force the curtailment of his expedition.

But there was a more present danger. On reaching Lhasa, Nain Singh had the bad luck to bump into a merchant from Leh who knew his identity and true occupation. The pundit feared betrayal and made plans to leave Lhasa immediately, rather than wait in the hope that the Lopchak mission might appear. Had he been able to delay his departure, he might have been able to retrieve his funds from the mission, even in the absence of the Lopchak himself.

Instead, the pundit sent two of his men back to Leh. They carried details of all his astronomical observations and route survey, and they reached Trotter safely in January 1875. Trotter now feared for the safety of his agent, who had in fact left Lhasa abruptly with his two remaining servants only two days after arriving. The psychological strain of possible discovery (followed by the inevitable imprisonment and probable death) must have told on the pundit, particularly as he had had to start off again from Lhasa with no chance to recuperate from a four-month march across the Chang Tang.

To return to India via Peking was clearly out of the question. The remaining funds were pitifully small. The best route to take home was the shortest and quickest, not northeast through China, but south into India.

In order not to arouse suspicion, and to throw pursuers off the track should he be betrayed, Nain Singh left his bulky inessentials behind with his landlord, saying that he would collect them ina month's time after returning from a pilgrimage to a monastery north of Lhasa. The small party duly left Lhasa for the north, but as soon as darkness fell made a 180-degree turn toward India. This fall-back strategy was inaccordance with his original instructions received from Walker and Trotter.

A week after leaving Lhasa, the pundit came to the Samye gompa, an ancient and famous monastery just two miles from the northern bank of the Tsangpo. He admired its high circular walls, which he estimated to be one and a half miles in circumference, and counted 1,030 chortens (funeral monuments) on top of it.

Nain Singh followed the course of the Tsangpo downstream for two days and then crossed it by boat. The river was sluggish, and the pundit was able to estimate its rate of flow as two-thirds of a mile per hour by throwing in a piece of wood and timing it over a fixed distance. Measuring the poles used to punt the ferry across the river gave it a depth of between eighteen and twenty feet. The river was about five hundred yards wide.

The point where the river was crossed was near the town of Chetang, and here Nain Singh left the Tsangpo. The information he was able to give about the river was valuable. He had followed it for thirty miles along a part of its course that had hitherto been unexplored. Chetang was fifty miles beyond the lowest point at which the river had been mapped to date, and from the town the pundit was able to approximate its course for a further one hundred miles by taking bearings of distant peaks, the Tsangpo being reputed to pass to one side of them.

Following the road south away from the Tsangpo, and up the valley of the Yarlung, one of its tributaries, Nain Singh crossed the main Himalayan chain by the Karkang pass, at a height of over sixteen thousand feet. He was traveling toward Tawang, accompanied by a man of some importance in that district. Tawang was a small area to the east of Bhutan and north of the Assamese plains, loosely owing an allegiance to Lhasa, and situated on a traditional trade route between India and Tibet. The merchants of Tawang were suffering at the hands of those in Lhasa and so were preventing any merchants from Tibet from proceeding onward to the Indian border, in order to retain the bulk of the trade for themselves. Because of this, the pundit, who had arrived in Tawang on 24 December, was detained there until 17 February, and not even his influential friend could prize him free before that time. Eventually, by depositing almost all of his remaining goods and by claiming that he would return for them after a pilgrimage just across the border, the pundit reached Udaiguri in British territory on 1 March 1875. There he presented himself to the local assistant commander, who telegraphed Trotter to announce the safe arrival of his explorer. The assistant commander also made the travel arrangements for the pundit to proceed to Gauhati, where he once again met up with the Tsangpo, now known as the Brahmaputra, and took a steamer to Calcutta.

The expedition had achieved important results, even though the pundit had been unable to reach his far-flung goal of Peking.

Nain Singh had traveled 1,405 miles between Leh and Udaiguri. His survey had started at Noh, a village whose position had also been fixed by the pundit Kishen Singh on his return from Khotan. It terminated at Udaiguri, the position of which was known very accurately from measurements made by the Indian Revenue Survey Department. Between these two points stretched 1,319 miles of virtually unknown country, of which 1,200 miles was completely unexplored. Prior to Nain Singh, only the small section around Tengri Nor had been surveyed, by Kishen Singh in 1872.

The pundit had located the eastern extremity of Lake Pangong, provided additional details of the Tibetan goldfields, mapped a large number of new lakes and rivers, and confirmed the existence of a chain of snow peaks to the north of the Tsangpo. More information on the course of this river through Tibet had been discovered. The route through Tawang to British India had been charted for the first time.

Nain Singh also took a large number of sextant observations, as well as pacing his route, taking compass bearings and measuring for altitude by observing the boiling point of water. All had to be made in conditions of complete secrecy Based on the pundit's earlier observations at Lhasa, Montgomerie had concluded that Lhasa lay at longitude 90 59' 30". All the measurements, said Trotter, showed the pundit to be "a skillful and accurate observer."

No Europeans were successful in reaching Tengri Nor until Bonvalot and Prince Henri of Orleans in 1890. A British expedition to the west of Tengri Nor almost half a century after Nain Singh (in 1922) commented that most of the information they had on the area was still derived from his expedition and that of Kishen Singh. They also verified the accuracy of the two pundits' observations.

This was Nain Singh's final foray beyond the frontiers. The stress of this journey and prolonged exposure to the elements had taken their toll on his health, and his eyesight in particular had been affected by continuous observations taken at very high altitudes. But although he retired from exploration, he continued to serve the Indian government with the training of younger explorers.

Within a year of his retirement, Walker was able to write that "he is an admirable trainer and has managed to collect several young men around him and taught them all that is necessary for work of this nature, so that they are now ready for further explorations." The work of teaching new recruits the fine art of secret exploration continued at least up until 1879, when "S.C.D." (Sarat Chandra Das) was given a course in surveying and observing by Nain Singh.

The pundit's name was now made public and was announced in the Geographical Magazine in 1876. Members of the GTS, including Walker and Montgomerie, urged that Nain Singh, in addition to his pension, should receive further monetary compensation from the government, as well as recognition from the Royal Geographical Society.

Montgomerie wrote to the India Office in March of 1877 from his home in Bath, pressing for a grant of land to be made to Nain Singh. Unknown to Montgomerie, this had already been done. On the recommendation of Walker, the Indian government had proposed to London on 15 December 1876 that the pundit be given the grant of a village in Rohilkand together with a jumma (or revenue assessment from land) of Rs. 1,000. These proposals were enthusiastically endorsed by the secretary of state for India in Council, who spoke of the "high value" of the pundit's achievements. The secretary of state also expressed "warm approval of the energy and discretion shown by Colonel Walker and Colonel Montgomerie in the gradual elaboration of a system which has produced, at a minimum of cost, results of real importance, which are seldom attained elsewhere without some considerable sacrifice of resources, if not of life."

The Paris Geographical Society had given Montgomerie a gold watch for him to send on to Nain Singh. Montgomerie did so, noting in a letter to Walker that "it is not a very handsome watch but the Society is not rich and they meant to pay N.S. a high compliment." The award of this watch came in the same year as the award of a gold medal from the Royal Geographicalal Society. It was the latter award, however, which occasioned considerable dissension in the highest councils of the "Geographical."

The question at issue was who was the most meritorious-Nain Singh for his feats of exploration, or Trotter for planning the expedition and interpreting and writing up the results? Clearly each accomplishment depended upon the other, but who should achieve recognition first?

On the one side was the former president of the RGS, Sir Henry Rawlinson, who proposed that Trotter should have the Patron's Medal for 1876 because of his "having conducted the Survey operations of the late Mission to eastern Turkistan under Sir Douglas Forsyth." This view was opposed by Colonel Henry Yule, whose views as a scholar carried much greater weight than those of Rawlinson. Yule wrote to Sir Rutherford Alcock at the Society, calling Nain Singh "the Pundit of Pundits," and comparing him with such giants of exploration as Livingstone and Grant. It was his "strong opinion," said Yule, "that his [Nain Singh's] great merits cannot be fully recognised by anything short of one of the Society's gold medals." Yule continued that "either of his great journeys in Tibet would have brought this reward to any European explorer; to have made two such journeys adding so enormously to accurate knowledge . . . is what no European but the first rank of travelers like Livingstone or Grant have done." Yule had been in touch with Walker, who was on leave in England at the time. Walker agreed with Yule and wrote that "I shall be very glad if you can get him the gold medal of the R. G. S., or any other suitable mark of distinction, in acknowledgement of his excellent services to geographical science." The letter, which did not mention Trotter, was sent along to the RGS by Yule......

.....The last words on Nain Singh are best left to Colonel Yule, addressing the Royal Geographic Society at the time of its presentation of the Society's gold medal. Nain Singh, he said, "is not a topographical automaton, or merely one of a great multitude of native employees with an average qualification. His observations have added a larger amount of important knowlege to the map of Asia then those of any other living man."