According to various statements available in Tamil literature from the Sangam age, Agattiyam, also known as Akathiyam, was the first known work on Tamil grammar. The book is considered to be composed by the sage Agastya and is regarded to be lost beyond recovery and redemption. The original work or any other genuine text from this grammatical work has not been recovered yet and thus the authenticity and the existence of the work on Tamil grammar is a matter of inference. There exist only few references to the ancient Tamil work in various other texts with respect to Agattiyam. The hermit Agastya is considered to be the architect and inventor of the Tamil language. According to Hindu mythology, the sage Agastya brought the language of Tamil and its syntax to the Dravidian people in the Tamil country from Lord Shiva himself. Agattiyam or Akathiyam is believed to be constructed by mythical hermit Agastya and Tolkappiyam, another work on Tamil grammar, is composed by Tolkappiyar, disciple of Agastya.

History of Agattiyam
The tradition and history of Tamil language is over two thousand five hundred years old. The initial recorded period of the Tamil literary works has been identified as the Sangam age of Tamil literature. During this ancient period, several literary masterpieces were composed by renowned Tamil poets and authors. Some of the most prominent works in Tamil literature includes the Eight Anthologies, the five epics, the Ten Idylls, and the two works on Tamil grammar, Tolkappiyam and Agattiyam. According to legends mentioned in the Sangam literature, Agastya was a sage and a linguist who came from the northern parts of India to the Deccan. The advent of this sage greatly influenced the Dravidian people and their languages with the impact of the Sanskrit language. Agastya incorporated Sanskrit into the various Dravidian languages that existed during that era and subsequently created a new language, Tamil. Moreover he also composed the grammar of Tamil language known as Agattiyam.

Moreover, it is believed that Agastya wrote the work of grammar at the great city of Madurai on the banks of the Vaigai River. Agastya had twelve disciples and Tolkappiyar was a member of the second Sangam. As the original text of Agattiyam is unavailable, Tolakappiyam is regarded as the earliest extant work of Tamil grammar. Tolakappiyar, a disciple of Agastya, was the writer of Tolakappiyam.