According to mythological legends, Alwar was a part of the Matsya region with Viratnagar as the capital. Alexander Cunningham postulated a theory that the city traced its name from the Salva tribe which was originally known as Salwapur then Salwar, Halawar and finally Alawar. According to the theory of origin states, the term Alwar comes from the Aravali hilly ranges. Some claim that it was named after Alaval Khan Mewati. while others says that Alwar city was founded by Maharaja Alaghraj in the eleventh century.
In some sources, it was formerly named as Ulwar. Pratap Singh worked in Jaipur Princely state and then joined British Imperial force as a soldier. He conquered Alwar fort and thereafter established his control over Alwar city. He assumed the title of Maharao Raja of Alwar and it remained a princely state till India’s independence. On 18th March 1948, the state accepted the offer to merge with the Union of India. In the beginning, it was merged with other three princely states, Bharatpur, Dholpur and Karauli to form Matsya division. On 15th May 1948, it was further merged with other princely states to form Ajmer state which later became a part of present day Rajasthan.
Rao Pratab Singh founded independent Alwar state. He was coroneted on 25th November 1775 at Alwar fort. He integrated regions such as Thanagazi, Rajgarh, Malakhera, Ajabgarh, Baldeogarh, Kankwari, Alwar, Ramgarh, Laxmangarh and nearby areas of Behror and Bansur to form Alwar Princely state. His reign collected revenue of 6-7 lakhs rupees per year. He was succeeded by his adopted son Bakhtawar Singh Prabhakar Bahadur.