Nagaur or Naga-Pur is referred to in the Mahabharata. The kingdom of Ahichhatrapur which Arjuna is said to have conquered and subsequently offered to his Guru Dronacharya, was perhaps some of the area of the Nagaur district. It was the capital of Jangladesh. The foundation of city dates back to 4th century BC. Nagas originally ruled over this place and about 7th century onwards the Chauhans became the overlords of Nagaur and it was included in Sapadalaksha.
Nagaur city was at the centre of Muslim invasion from Central Asia. The Nagaur fort is of historical importance. The Rajput rulers who dominated Nagaur for a longer period. Nagaur ruler were repeatedly forced to pay tribute to the Sesodias of Chittor while their lands were slowly annexed by the Rathors of Jodhpur. In fact the case of Nagaur vividly illustrates the turning back of the tide of Islamic conquests in Rajputana in the 14th and 15th Centuries.Nagaur, north to Bikaner, and up to the border of Punjab, was called Jangladesh in ancient times. The remains of some of the earliest settlements along the banks of the long dried-up Saraswati River can be seen to this day—in a later age it came under the Naga rulers after whom the town of Nagaur (Naga-pura) is named.
The name of Jangladesh was known till a very late period. The Rajput rulers of Bikaner, whose territory eventually embraced the bulk of Jangla country, sported the title Jai Jangaldhar Badshah, which was emblazoned on the state coat of arms during the British Raj. In the medieval era the town of Nagaur sat astride trade routes coming north from Gujarat and Sindh and those on the west crossing the Indus from Multan. With a dead flat plain all around, the defense of the fort depended on the military and economic power of its rulers—and from the period of the Ghaznavid invasions Nagaur was under the powerful Chauhan clan. A succession of rulers kept the whole of Jangladesh free from foreign rule down to the reign of Prithviraj Chauhan
