In Indian Mythology, Nagas were Serpents who lived beneath the Earth in magnificent palaces.
The Nagas sometimes appeared as humans or monsters.
The Nagas also had a very important esoteric role.
Gautama imparted the Doctrine of the universal Void to the Nagas.
Seven centuries later, the sage Nagarjuna was initiated by the Nagas into the esoteric truth, and thereby brought forth the doctrine which distinguishes Mahayana Buddhism from its Hinayana Counterpart.