The Jambheswar fair is in honour of Jambheswari who is the founder of the Bishnoi sect. Every year two fairs are held in his honour on Phalgun Budi Amavasya and Ashivan Budi Amavasya in Mukm village in Bikaner district. Phalgun Budi Amavasya is the biggest fair.
The Bishnois form a separate sect and do not mix with other Hindus and worship Vishnu in his Jambhaji incarnation. The Bishnois believe that the city of Viskramaditya, with its throne of gold, is buried beneath the sand dune where the saint died. Jambheshwarji was the thirty-second descendant of Vikramaditya. According to legend, he was found under a tree and tended cows till the age of twelve. He is supposed to have been dumb in childhood but wrought a self-miracle which gave him speech. He later gave up the occupation of cowherd and settled down on the top of a hill where he gave the Bishnois the twenty-nine articles of their religion. The word 'Bisnoi' is a combination of 'bees' (twenty) and 'noi' (nine)- The followers of the twenty-nine articles of faith laid down by Jambeshwarji.