According to Punjab states Gazetteer-Shimla hill States from 1803 to 1815 the earstwhile states of Bushahr faced the menace of Gurkha invasions. Immediate after the death of Raja Kehri Singh, The Gurkhas made massive attack on Bushahr. The minor ruler and his mother who could not withstand the attack fled away to Namru leaving behind a rich treasury at Sarahan. The Gurkhas looted the treasury and completely destroyed the records of the state. Keeping Gurkhas of Nepal had extended their dominions greatly during the end of the eighteen century. Amar Singh Thapa, the Gurkha leader went up to kangra valley. He was drawn from the valley by the superior forces of Ranjit Singh and those of raja Sansar Chand of Kangra. The tract between the Satluj and Jamuna came under British protection by the treaty of 1809 between Ranjit Singh and the British Govt. Thus the British Government took positive step to expel the Gurkhas and after a long and desperate struggle, completely defeated Amar Singh Thapa on 15 th April, 1815. On the conclusion of the Gurkha war Raja Mahendra Singh was granted a sanad on 6th November,1815. It gave Khaneti and Delath thakurais to Bushahr and a part of Rawin, which was a Distt. of the state was transferred to Keonthal, Kumharsain was constituted a separate Thakurai.
From the foregoing account it would appear that during the princely days Kinnaur valley acted as a bulwark to the Bushahr state. However with the lapse of paramountcy, the Kinnaur then known as Chini tehsil was merged to form a part of then Mahasu district. The pargana Atharahs Bish comprised of village Nichar, Sungra, Kangos, Ponda, Baro, Bari, Tranda, Chaura village with patwar circle at Ponda. The Paragana Bish consisted of the revenue estates of Nathpa, Kandhar, Barakamba, Chhotakamba, Garshu and Rupi with patwar circle at Rupi were in Rampur tehsil.
In fact then Chini tehsil covered the entire Kinnaur valley beyond Wangtu which was created in 1891 by the then ruler Tika Raghunath Singh. Thus 1891 onwards Chinni tehsil continued to be in existence with its vast area beyond Wangtu uptill 1960. Since 1947 it was a tehsil of the then Mahasu district. By 1960 the importance of reorganising border area was realised and consequently in view of ethnic and cultural considerations the areas which were partly in Rampur tehsil were reorganised into a separate District forming the present Kinnaur district.