The Pothigai Hills, also known as Agasthiyar Mountain is a 1,866-metre (6,122 ft)-tall peak in the southern part of the Western Ghats or Sahyadri of South India.

[10] The Pothigai hills are mentioned as Potiyil, Potiyal, Pothikai and Potalaka in historical sources largely in relation to the river Tamraparni and the ancient Sage Agastya (Akattiyan).

[17] The shrine to Agastiyar at the Pothigai hill source of the Tamraparni river is mentioned in both Ilango Adigal's Silappatikaram and Chithalai Chathanar's Manimekhalai epics, in relation to blessings sought by Sugriva and his army from the Ramayana.

Chithalai Chathanar's Manimekhalai describes a river flowing on the slope of Potiyil mountain where the Buddhist monks observed meditation.

[19] In fellow Sangam work Kuṟuntokai of the Eṭṭuttokai anthology, a Buddhist vihara under a Banyan tree is described at the top of the mountain.

A comment that God had disappeared from the mountain was found in Ahananuru, from whose inaccessible top the stream of clear waters flows down with noise in torrents, and the fact that old men assembled and played dice in the dilapidated temple is described in Purananuru.

[20] The Japanese scholar Shu Hikosaka on the basis of his study of Buddhist scriptures, ancient Tamil literature, as well as field survey, proposes the hypothesis that, the ancient mount Potalaka, the residence of Avalokiteśvara described in the Gaṇḍavyūha Sūtra and Xuanzang’s Records, is the real mountain Pothigai (or Potiyil) situated at Ambasamudram in Tirunelveli district, Tamil Nadu.

With the spread of Buddhism in the region beginning at the time of the great king Aśoka in the third century B.C.E., it became a holy place also for Buddhists who gradually became dominant as a number of their hermits settled there.

The eastern side of the hills in Tamil Nadu includes the Kalakkad Mundanthurai Tiger Reserve (KMTR), a 895 square kilometres (346 sq mi) protected area.

The Naraikadu forest or "grey jungle", surrounded by the Kalakad Mundanthurai Tiger Reserve, is privately owned by the Dhonavur Fellowship.

[citation needed] Many pilgrims climb Agasthyamalai in the core of the hills to perform a puja ceremony at the Agasthya Murti on the top the Peak.

[citation needed] The Chief Conservator is responsible for on-site management of the protected areas on the Kerala side of the Hills.