Solan District came into existence at the time of the reorganisation of the districts of the State on Ist September, 1972. The District was carved out of Solan and Arki tehsils of the then Mahasu district and tehsils of Kandaghat and Nalagarh of the then Shimla District. Administratively, the district is divided into four Sub-division viz. Solan comprising of Solan and Kasauli tehsils, Nalagarh covers the juridisdiction of Arki and Kandaghat Sub-divisions covers their respective tehsils. The total geographical area of the district according to the Surveyour General of India is 1,936 sq. km. which constitutes 3.49 percent of the total area of the State and ranks 9th amongst the district.
The District is bounded by Shimla district in the North and by Ropar District of Punjab and Ambala district of Harayana in the south, by Sirmaur District in the east and by Bilaspur district in the west. Mandi District touches the boundary of Solan district in norht-east. The shape of the district is rectangualar with slight bulge on the northern side intruding towards Mandi district.It is located between the longitudes 76.42 and 77.20 degree and latitudes 30.05 and 31.15 degree north. the elevation of the district ranges from 300 to 3,000 metres above eas level. The mountain ranges lie in the outer Himalayas and are a part of Shivalik ranges. The mountains of lower elevation are found in western-southern parts of the distict comprising of Nalagarh and Arki tehsils while higher ranges start from central region and extend upto north-estern corner of the District comprising Solan tehsil and parts of Arki tehsil, Kasauli tehsil and Kandaghat tehsil which are located in north-eastern direction of the district and are having the highest ranges of the District.
The district in its present form comprises of the erstwhile princely states of Bhagal, Bhagat, Kunihar, Kuthar, Mangal, Beja, Mahlog, Nalagarh and parts of Keonthal and Kothi and hilly areas of composite Punjab State which were merged in Himachal Pradesh on the Ist November, 1966 on the reorganisation of composite Punjab on the linguistic basis. Most of these princely state as per history were subjected to the onslaught of Gorkha invasion from the year 1803 to 1805. it was in the year 1815 that after th gorkhas lost to the Britishers, these states were freed and restored tot he respective rulers. Most of the states were small in area and population and were under the control of the superintendent of Shimla Hill States before Independence. Himachal Pradesh appreared on the administrative map of the country on the 15th April, 1948 and the states of Bhagat, Baghal, Kunihar, Kuthar, Mangal, Beja, Keonthal and Koti formed a part of the then Mahasu District. Nalagarh state which was merged after Independence in Patiala and East Punjab State Union later on formed a part of Punjab when the reorganisation of the states took place in 1956 and remained a tehsil of Ambala District, Kandaghat and Shimla tehsils of Shimla district like othe rhilly areas of Kullu, Lahul and Spiti and Kangra districts become part of Himachal Pradesh on the Ist November, 1972 and Solan District sprang up on the administrative map of the state
Solan District derives its name from Solan town which came into existence after the construction of the Cantonment at that palce around the last quarter of the 19th century
Old States :-
The name is popularly derived form Bau or Bahu said to be a hilly word meaning many and Ghat meaning pass. Others are of the view that it ia s misnomer of Baraghat(12). There are certainly many places in the erstwhile Bhagat state which are known as Bhagat State which are known as Ghat. The state headquarters of the Bhagat State was located at Bhoch in the Bhuchali pargana. The headquarter was shifted to solan after the construction of Cantonment at that place. The founder of the ruling family is said to be Basant Pal or Hari Chand Pal, a Panwar Rajput from Dharana Giri in the Deccan.
The ruling family of the state traces its origin from Aje De a panwar Rajput who came from Ujjain. In the year 1905, there was a revolt by the entire Kanet population which was put down with the help of the Superintendent of Shimla Hill state. Thereafter, the state was put under the charge of the Manager and the Tikka was installed as Raja of the state. The last ruler was Raja Rajindra Sing and the state was merged in Himachal Pradesh in 1948 and remained a part of Mahasu district till 31st August, 1972.
The state was founded by Abhoj Deo who had come form Akhnur in Jammu and acquired the state by conquest about the year 1154 A.D. Most of his descendents were keen warrier and they assisted Nalagarh and Bilaspur rulers in their various wars mainly against Kullu. During the region of Keso Rai who ruled over the state during 1600 A.D., the affairs of the state began to fall as the ruler was a weak and indolent with the result the neighbouring states seized portion of the territory.
Surat Chand, the founder of the ruling family is said to have come from Kishtwar in Kashmir and is said to have acquired the state by conquest. At the time of Gorkha invasion, Rana Gopal Chand was the ruler. The state was restored by the Britishers. The state was merged with Himachal Pardesh in April, 1948 and remained part of the then Mahasu district till August, 1972.
The ruling family of the state traces its origin to Bir Chand, Raja of Ajudhia who visited Mansrover Lake on the directions from Lord Shiva in a dream. On his way back, he expelled the Mawis in the neighbourhood of Bhawana and established the kingdom of his own. During the time of Ajit Chand, Raja of Kangra annexed 9 or 10 pargana of Mahlog state and handed over the same to Bhagat and thenceforth the Mahlog Chief was known as Rana instead of Raja. The state was restored to Ajit Chand by the Britishers after the Gorkha war. The later rulers were Sansar Chand, Raghunath Chand and Durga Chand etc. The state was merged with Himachal Pradesh in 1948 and formed a part of Solan tehsil of the then Mahasu District.
The ruling family of teh state was belonging to the Rajput of Tunar Got and is said to have hailed from somewhere in the neightbourhood of Delhi. Bishan Chand was the chief at the time of Gorkha invasion. The state was restored to him under the title of Thakur.
Mangal was the most inaccessible of all the hill states. Originally, it was a tributory to Bilaspur and was declared independent at the end of the Gorkha war. The ruling family is said to have come from marwar and belonged to Atri Tribe of Rajpur Community.