Wikipedia
Pothigai
The Pothigai Hills, also known as the Agasthiyar Malai are in the Ashambu Hills, part of the Anaimalai Hills in the southern part of the Western Ghats of South India. Ancient tradition holds the mountains of Pothigai to be where the sage Agastya (Akattiyan) provided the first grammar for the Tamil language. This grammar was further fine tuned by one of his disciples in the Tolkāppiyam.