Sawai Jai Singh II (3 November 1688 – 21 September 1743), was the 29th Kachwaha Rajput ruler of the Kingdom of Amber, who later founded the fortified city of Jaipur and made it his capital.

[1][5] In the later part of his life Sawai Jai Singh broke free from Mughal hegemony, and to assert his sovereignty, performed the Ashvamedha sacrifice, an ancient rite that had been abandoned for several centuries.

[8] Sawai Jai Singh II other than administration and state craftship had a profound interest in the fields of Mathematics, Architecture, Astronomy, Astrology and Literature.He commissioned the Jantar Mantar observatories at multiple places in India, including his capital Jaipur.

[11] His feat of arms at the siege of Khelna (1702) was rewarded with the mere restoration of his earlier rank and the title of Sawai (meaning one and a quarter, i.e., more capable than one man).

Sawai Jai Singh formed an alliance with the Rajput states of Mewar (matrimonially) and Marwar against Mughal Emperor Bahadur Shah I.

Imperial power had by then been crippled by the rebellion of the Nizam of Hyderabad as well as the ability of Peshwa Baji Rao to stabilize the internal situation of the Marathas, which resulted in their occupation of Gujarat and an immense increase of their forces.

Nonetheless, in the name of the friendship between their royal ancestors, Jai Singh II, was able to appeal to Shahu to restore to the imperialist, the great fortress of Mandu which the Marathas had occupied a few weeks earlier (order date 19 March 1730).

[16] According to an estimate by Jadunath Sarkar, Jai Singh's regular army did not exceed 40,000 men, which would have cost about 60 lakhs a year, but his strength lay in the large number of artillery and copious supply of munitions which he was careful to maintain and his rule of arming his foot with matchlocks instead of the traditional Rajput sword and shield - He had the wisdom to recognize early the change which firearms had introduced in Indian warfare and to prepare for himself for the new war by raising the fire-power of his army to the maximum,[clarification needed] he thus anticipated the success of later Indian rulers like Mirza Najaf Khan, Mahadji Sindhia and Tipu Sultan.

Jai Singh's experimental weapon, the Jaivana, which he created prior to the shift of his capital to Jaipur, remains the largest wheeled cannon in the world.

The armed strength of Jai Singh had made him the most formidable ruler in Northern India, and all the other Rajas looked up to him for protection and the promotion of their interests at the Imperial court.

To thwart further Maratha expansion, Sawai Jai Singh planned the formation of a local hegemony, led by Jaipur, and a political union in Rajputana.

To this end, he annexed Bundi and Rampura in the Malwa plateau, made a matrimonial alliance with Mewar, and intervened in the affairs of the Rathors of Bikaner and Jodhpur.

These half-successful attempts only stiffened the backs of the other Rajput clans, who turned to the Marathas for aid, consequently hastening that state's domination over Rajasthan.

[18][19] Jai Singh was the first Hindu ruler in centuries to perform ancient Vedic ceremonies like the Ashwamedha sacrifices (1716)[20] and the Vajapeya (1734); on both occasions, vast amounts were distributed in charity.

It was at Jai Singh's insistence that the hated jaziya tax, imposed on the Hindu population by Aurangzeb (1679), was finally abolished by the Emperor Muhammad Shah in 1720.

Despite local wars, foreign invasions, and consequent turmoil, Jai Singh found time and energy to build astronomical observatories.

Merchants from all over India settled down in the relative safety of this rich city, protected by thick walls and a garrison of 17,000 (including adequate artillery).

The Sanskrit epic 'Ishvar Vilas Mahakavya', written by Kavikalanidhi Devarshi Shrikrishna Bhatt, recounts various important events of that era, including the construction of Jaipur city, in detail.