The Agnikunda legend gives an account of the origin of the Agnivanshi Kshattriyas. In fact, it attempts to explain the origin of some of the Rajputs. There are several versions of the legend.
The Bhavishya Purana version of the legend begins with the puranic legend wherein Parashurama, an avatara of Vishnu, exterminated the traditional kshatriyas of the land. Later, the legend says, sage Vasishta performed a great Yajna or fire-sacrifice, to seek from the gods a provision for the defense of righteousness on earth. In answer to his prayer, a youth arose from the Agnikunda or fire-altar -- the first Agnivanshi Rajput. According to different versions of the legend, one or three or four of the Rajput clans originated from the Agnikunda, including the Naru Rajputs (Naru means Fire), Pratiharas (Pariharas), Chauhans (Chahamanas), Solankis, and Paramaras (Parmars)(Rahevar)(Rever).This legend is explained up to some extent if one tries to look into Bhavishya Purana