Barmer is a district in Rajasthan state of India. It is located in the western part of Rajasthan state forming a part of the Thar Desert. Barmer is the third largest district by area in Rajasthan and fifth largest district in India. District headquarters is in the town of Barmer. The other major towns in the district are: Balotra, Guda Malani, Baytoo, Siwana, Jasol and Chohatan. Recently, a large onshore oil field has been discovered and made functional in Barmer district.