The two units of the district i.e. Lahaul & Spiti, have separate historical backgrounds. In the distant past Lahaul had been changing hands between the rulers of Ladakh and Kulu. In the second half of the seventeenth century with the disintegration of Ladakh kingdom, Lahaul passed into the hands of the Kulu chief. In 1840, Maharaja Ranjit Singh took over Lahaul along with Kulu and ruled over it till 1846 when the area came under the sway of the British. From 1846 to 1940, Lahaul formed part of the Kulu sub-division of Kangra district and was administered through the local jagirdars/thakurs. One of the thakurs was designated as Wizier of Lahaul & was invested with judicial and executive powers. Another thakur was given the powers of a Revenue Officer. These functionaries exercised traditional as well as other power conferred by the Government. The Assistant Commissioner. Kulu used to visit the area once a year for a month or so. In the late thirties the unprecedented prosperity of the people through growing kuth and their consequent awakening created a formidable challenge to the power and influence of the Wizier of Lahaul, which gradually started declining. The inadequacy was soon noticed by the Government which considered the extension of the regular system of administration. Accordingly in 1941, a separate sub-tehsil comprising Lahaul & Spiti was formed and a naib-tehsildar was posted at Keylong thereby divesting the thakurs of their powers. The system remained in vogue till June, 1960 when Lahaul & Spiti district came into being. Simultaneously, Lahaul was constituted into a separate tehsil, and, later on it was formed into a sub-division.
The East India Company took over the possession of the Spiti portion in the year 1846 after the cessation of cis-Satluj States as a result of the Anglo-Sikh War. Before that it formed a part of Ladakh, a subsidiary of Jammu & Kashmir. Because of its remoteness and poverty of natural resources, the British following the example of the Ladakhi rulers, did not introduce any substantial changes in the administrative set up of the territory. The Nono of Kyuling was recognized as the hereditary Wizier of Spiti (re-affirmed by the Spiti Frontier Regulations of 1883) and was suppose to represent the British India Government. He collected the land revenue for the Government, his judicial jurisdiction included trial of all criminal cases, except cases of murder; and he performed all functions and enjoyed all necessary powers for the fulfillment of his tasks and duties, as laid down in the regulations of 1883.
In 1941, Spiti,with Lahaul, was constituted into a separate sub-tehsil of Kullu sub-division which had its headquarters at Keylong. Later on, after the formation of Lahaul & Spiti into a district, in 1960, Spiti was formed into a sub-division with its headquarter at Kaza.