The erstwhile state of Alwar, in north-eastern Rajasthan, is possibly the oldest kingdom in kingdom-studded Rajasthan. In 1500 BC it formed part of the Matsya territories of Viratnagar (present-day Bairat), which also encompassed Bharatpur, Dholpur and Karauli.

History becomes inextricably bound with mythology, as it was here in the ancient kingdom of Matsya that the Kauravas embarked on the cattle-rustling mission which precipitated the war between and their kinsfolk, the Pandavas. This battle forms the basis of the Mahabharat.

The city of Alwar is believed to have founded by a member of the Kachh family who hailed from Amber, but control was wrested from the Kachhwahas of Nikumbhas. They in ruin lost the city to Bada Gurjara Rajputs of Machari. It passed to the Khanzadas, under Bahadur Nahara of Mewat, who converted from Hinduism to Islam to win the favour of Emperor Tughlaq of Delhi. At this time, Alwar was part of the kingdom of Mewat.

Descendants of Bahadura Nahara defended the Alwar fort against the Muslims in 1427. Alwar's fortunes were inextric bound with those of Mewat, which was contiguous with Delhi. Although the Mewat leaders professed the Muslim faith, he continue to ally himself with the Rajputs.

As Alwar located on the strategic south-western side of Delhi, this of course rankled with Mughals, who mounted numerous miliitary forays into the region, conquere it after great difficulty. Alwar was later granted to Sawai Jai Singh of Jaipur by Aurangzeb. It was retaken when the emperor visited the city and noted the great strategical virtue of its fortress.

The Jats of Bharatpur then threw their hat into the ring, briefly overrunning the region, and installing themselves in the Alwar fort. They were evicted by the Lalawat Narukas (descendants of the Kachhwaha prince of Amber, Naru) between 1775 and 1782 under the leadership of the Naruka thakur (noble) Pratap Singh. His descendants were great patrons of the arts , commissioning the transcription of numerous sacred and scholarly texts and encouraging painters and artisans to visit the Alwar court.

In 1803, the British awarded the Alwar thakur with the title of maharaja as thanks for their support in a battle against the Marathas. This friendly alliance was short-lived, however, with the maharaja of Alwar strongly resenting British interference in governance when a British Resident was installed in the city.

Following Independence, Alwar was merged with the other princely states of Bharatpur, Karauli and Dholpur, forming the United State of Matsya, a name which reflected the fact that those states all comprised the ancient Matsya kingdom.

In 1949, Matsya was merged with the state of Rajasthan.