According to Matsyapurāṇa (Matsyapurana), Udbhava was one of the seven sons of Rājarṣi  (Rajarshi; a king with the virtues of a saint) Nahuṣa(Nahusha) belonging to Candravaṁśa (Chandravamsa).

Matsyapurāṇa(24.50)