Nishadas are mountain dwelling tribes and they existed from time immemorial. The word nishad means an instruction to sit. The story of origin of Nishadas is found in the Harivamsa and is associated with King Vena.
In the great lineage of Dhruva, there was a king named Anga. He had a son named Vena, who was cruel and arrogant from childhood. When he became king he stopped all sacrifices and oblations.
King Vena announced – “I am the one who should be worshipped through sacrifices. I am the sacrifice and the one who sacrifices”.
The great rishis requested the king not to practice Adharma. But the king was not ready to change his ways.
Vena arrogantly announced – “Who other than me is the creator of dharma? Who other than me should be listened to? There is no doubt that you do not know of my superiority because of your folly. If I desire, I can burn the earth down or flood it with water. Without even thinking about it, I can slow down the progress of the firmament and this earth."
The maharshis tried to persuade the king to give up Adharma. But he was filled with insolence and arrogance.
The maharishis under the leadership of Sage Marichi became angry. The combined power of the maharishis subdued King Vena.
They kneaded his left thigh and a man manifested from the thigh. The man was short and dark. The Maharishis asked him to sit. He was the progenitor of the lineage of nishadas.