The Nag’s were the race of serpents or snakes who were born from Kasyapa-pra- japati (a progenitor) by his wife Karda. Many had divine powers and were neutral as far as their relationship with the gods was concerned. It was their great power that made them threatening to humans.
When Bala-Rama, brother of Krishna, died, his spirit left his body through his mouth as a white serpent and was welcomed into the netherworld by the Naga kingdom. Prince Candrangada was rescued by the Naga king Takshaka and lived in his kingdom for a while, even marrying the Naga princess Ulupi.
Nevertheless, Nagas were also dangerous, having absorbed the venom (halahala) that was churned up from the Milky Ocean. Garuda, the sun eagle, was their natural enemy, eating them as his preferred food. Vasuki, Kaliya, and Takshaka were among the most famous Nagas.
In some lists Nagas were classified as minor gods or devas.