Yaudheya or Yaudheya Gana was an ancient confederation who lived in the area between the Indus river and the Ganges river. They find mention in Pāṇini's Ashtadhyayi and Ganapatha. There are other references to them namely in Mahabharata, Mahamayuri, Brihatsamhita, Puranas, Chandravyakarana and Kashika. As references are spanned from writings of early period to the medieval period, the chronology of Yaudheyas perhaps spans from as early as 500 BCE till 1200 CE. They were in zenith of their power from about 200 BCE to 400 CE.
Puranas (e.g. Brahmanda, Vayu, Brahma and Harivamsha) described Yaudheyas as the descendants of Usinara and Nrigu.
The earliest mention of Yaudheyas is in Ashtadhyayi (V.3.116-17 and IV.1.178) of Pāṇini (c.500 BCE) where Yaudheyas are mentioned amongst Ayudhajivin Sanghas.
Later, the Junagadh rock inscription (c. 150 CE) of Rudradaman I acknowledged the military might of the Yaudheyas "who would not submit because they were proud of their title "heroes among the Kshatriyas"", although the inscription claims that they were ultimately vanquished by Rudradaman.
Rudradaman (...) who by force destroyed the Yaudheyas who were loath to submit, rendered proud as they were by having manifested their' title of' heroes among all Kshatriyas.
The Allahabad pillar inscription of Samudragupta also mentioned about the Yaudheyas. Varahamihira in his Brihatsamhita (XIV.28 and XVI.22) placed them in the northern division of India.
Kumāra Karttikeya with vel and rooster, coin of the Yaudheyas
Six-headed Karttikeya on a Yaudheya coin. British Museum.