Yadav refers to a group of communities or castes found in India and Nepal, which claim descent from the ancient King Yadu of the Chandravanshi Kshatriya clan. Yadav is one five Indo-Aryan Kshatriya clans mentioned in the Vedas as "Panchjanya". The Yadavas generally follow the Vaishnava tradition of Hinduism, and share dharmic religious beliefs Yadavs are traditionally classified under the Kshatriya varna in Hinduism, and several royal dynasties in medieval India claimed Yadav descent. They remained in power in India and Nepal until 1200-1300 CE, before the arrival of Muslim invaders.
In modern times, the communities claiming Yadav descent include Ahirs,Bhati, Saini, Jadon and other Yaduvanshi castes.
Yadu was the eldest son of Yayati (father of Yadavs). It is written in the Vishnu Puran that he did not inherit his father's throne. He, therefore, retired towards Punjab and Iran. He had five sons, of whom except Satjit and Krishna, three remained childless. Satjit had three sons: Bibai (Biveya), Hai (Heya) whose descendants are Jats of the Heer gotra and Ahai (Aheya) who founded the Ahir community.
Yadavs are the descendants of Yadu, the eldest son of King Yayati. It is said that Yadu was expelled by Yayati from his kingdom and became a rebel. His successor was Madhu, who ruled from Madhuvana, situated on the banks of river Yamuna, which extended up to Saurastra and Anarta (Gujrat). His daughter Madhumati married Harinasva of Ikshvaku race, from whom Yadu was born again, this time being ancestor of Yadavas. Nanda, the foster father of Krishna, was born in the line of succession of Madhu and ruled from the same side of Yamuna. Jarasandh, Kansa's father-in-law, and king of Magadha attacked Yadavas to avenge Kansa's death. Yadavas had to shift their capital from Mathura (central Aryavart) to Dwaraka (on the western coast of Aryavart) on the Sindhu. Yadu was a legendary Hindu king, believed to be an ancestor of the god Krishna, who for this reason is sometimes referred to as Yadava.
Ramprasad Chanda, points to the fact that in the Indra is said to have brought Turvasu and Yadu from over the sea, and Yadu and Turvasu are called Barbarian or Dasa. After analyzing the ancient legends and traditions he comes to the conclusion that Yadavas were originally settled in the Kathiawar peninsula and subsequently spread to Mathura.
Of the Yadus, rigveda provides two very interesting data, first, that they were arajinah - without King or non-monarchical, and second that Indra brought them from beyond the sea and made them worthy of consecration. A. D. Pusalkar observed that Yadvas were called Asuras in the epic and puranas, which may be due to mixing with non-aryans and the looseness in observance of Aryan Dharma. It is important to note that even in the Mahabharata Krishna is called Sanghmukhya - Head of Sangh (congress). Bimanbehari Majumdar points out at one place in the mahabharata Yadavas are called Vratyas and at another place Krishna speaks of his tribe consisting of eighteen thousand vratyas. It is interesting to note that much later,
Abhira of Deccan were called Andhra-Vratyas, and Purunas refer to them as Vratyas on many occasions. A Vratya is one who lives outside the fold of the dominant Aryan Society and practice their own form of austerity and esoteric rites. some scholars conjecture that they might have been the source of non-aryan beliefs and practices introduced into Vedic religion.
Ahirs as Yadavas:
Ahir (Sanskrit Abhira अभीर "fearless") is a Hindu caste, which is subgroup of Yadav and mentioned as a foreign tribe of Indo-Scythians. Besides scriptural origin, historical evidence exists for identifying the Ahirs with the Yadavas. The term Ahir comes from Abhira (Bhandarkar, 1911;16), who where once found in different parts of India, and who in several places wielded political power. Ancient Sanskrit classic, Amarkosa, calls gwal, gopa & ballabh to be the synonym of Abhira.A Chudasama prince styled Grahripu and Ruling at Vanthali near Junagarh described in the Dyashraya kavya of Hemachandra, describes him both as a Abhira and a Yadav. Further, in their Bardic traditions as well as in popular stories Chudasmas are still called Ahir Ranas. Again, many remains of Khandesh (historical stronghold of abhiras) are popularly believed to be of Gawli Raj, which archaeologically belongs to the Yadvas of Devgiri. Hence, it is concluded that Yadavas of Devagiri were actually Abhiras.
Moreover, there are sufficient number of clans within Ahirs, who trace their lineage from Yadu and Lord Krishna, some of which are mentioned in Mahabharata as Yadav Clans. James Tod demonstrated that Ahirs were included into the list of 36 royal races of Rajasthan.