[1] No authentic records of the exact dates of establishment of temple exist, though it is beyond dispute, that Thirunelli was once an important town and pilgrim center in the middle of an inaccessible jungle valley surrounded by mountains on four sides.

There exists documentary proof that Thirunelli at the time of Chera king Bhaskara Ravi Varma I (962–1019 CE) was already an important town and pilgrim center in South India[citation needed].

Noted historian V. R. Parameswaran Pillai in his book Thirunelli Documents states that this temple was once an integral part of the early recorded history of Kerala.

[3][4] Emanating from the heart of Brahmagiri forest flowing through roots, leaves and flowers of ancient trees and medicinal herbs, Papanasini is a holy mountain stream accessible around 1 km northwest of the temple premises.

Further, the temple offers services to immerse cremation ashes in the sacred mountain stream to be thus carried to Kaveri River and from there to the ocean.