Nain Singh Rawat
Nain Singh Rawat (21 October 1830 – 1 February 1882), was one of the first of the late 19th century Indian explorers (pundits) who explored the Himalayas for the British. He hailed from the Johar Valley of Kumaon. He surveyed the trade route through Nepal to Tibet, determined for the first time the location and altitude of Lhasa, and surveyed a large section of the Brahmaputra. He walked "1,580 miles, or 3,160,000 paces, each counted."

Early life
Rai Bahadur Nain Singh Rawat was born to Lata Burha in 1830 in Milam village, a Bhotia village at the foot of the Milam glacier where the river Goriganga originates in the valley of Johar now on India-China border now in present day Pithoragarh district of Uttarakhand state of India. The Rawats ruled over the Johar valley, during the reign of Chand dynasty in Kumaon; this was followed by the Gorkha rule. In 1816 the British defeated the Gorkhas but maintained a policy of non-interference and friendship towards the Johar Bhotias. The famous Bhotia explorers mostly belong to the village of Johar.

After leaving school, Nain Singh helped his father. He visited different centres in Tibet with him, learned the Tibetan language, customs and manners and became familiar with the Tibetan people. This knowledge of Tibetan language and local customs and protocol came in handy in Nain Singh's work as a "spy explorer". Due to the extreme cold conditions, Milam and other villages of the upper Johar valley are inhabited only for a few months from June to October. During this time the men used to visit Gya'nyima, Gartok and other markets in Western Tibet.

During his secret survey of Tibet, Nain Singh was the first non-Tibetan to visit many legendary areas of Tibet, including the Thok Jalung goldfields on 26 August 1867. He would later say that Thok Jalung was the coldest place he had ever visited.

Nain Singh was a cousin of Krishna Singh Rawat (1850-1921), also an explorer and cartographer, who was first to map the Ramgarh crater on a finer scale of (1 : 63,360).

Legacy
On 27 June 2004, an Indian postage stamp featuring Nain Singh was issued commemorating his role in the Great Trigonometric Survey. In 2006, Shekhar Pathak and Uma Bhatt brought out a biography of Nain Singh with three of his diaries and the RGS articles about his travels in three volumes titled Asia ki Peeth Par published by Pahar, Naini Tal.

The Nain Singh Range of mountains south of Lake Pangong are named in Nain's honour.

On 21 October 2017, Google celebrated Nain Singh Rawat's 187th birthday with a Google Doodle.