History of Lahaul and Spiti District deals with the reign of Maharaja Ranjit Singh. As per researchers, the two units of Lahaul and Spiti District that are Lahaul and Spiti have separate historical backgrounds. In the distant past Lahaul had been changing hands between the rulers of Ladakh and Kullu. In the second half of the seventeenth century with the disintegration of Ladakh kingdom, Lahaul passed into the hands of the Kullu chief. In 1840, Maharaja Ranjit Singh took over Lahaul along with Kullu and ruled over the region till 1846 when the area came under the sway of the British rulers.

From 1846 to 1940, Lahaul formed part of the Kullu sub-division of Kangra District and was administered through the local jagirdars or thakurs. One of the thakurs was was invested with the judicial and executive powers. Another thakur was given the status of a Revenue Officer. These functionaries exercised traditional as well as other power conferred by the government. The Assistant Commissioner of Kullu used to visit the area once a year for a month or so. In the late thirties the unprecedented prosperity of the people and their consequent awakening created a formidable challenge to the power and influence of the thakur 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 and 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 and Spiti district came into being. Simultaneously, Lahaul was constituted into a separate tehsil, and, later on it was formed into a sub-division.

The British East India Company took over the possession of the Spiti portion in the year 1846 as a result of the Anglo-Sikh War. Before that it formed a part of Ladakh, a subsidiary of Jammu and 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 Wazir of Spiti (re-affirmed by the Spiti Frontier Regulations of 1883) and was supposed to represent 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 and Spiti into a district, in 1960, Spiti was formed into a sub-division with its headquarters at Kaza.