This section is from the book "Some Contributions Of South India To Indian Culture", by S. Krishnaswami Aiyangar. Also available from Amazon: Some Contributions of South India to Indian Culture.
This makes it clear that the literature of the the South taking into consideration only the literature extant, is essentially Aryan in character, exhibiting, no doubt, occasional features other than Aryan which get absorbed into the system. Buddhist and Jain works must necessarily have this character of the northern literature by the very necessities of their origin; not so the Hindu part of the literature of the Tamils. These show unmistakably their Brahmanical character, not because they necessarily originated from or were handled by the Brahmans, -and this feature is to a great extent true - but because of something deeper still than that. Writers who were Buddhists and Jains, writers that were not Brahman exhibit this special character of the literature that has come down to us. It is possible to refer to numbers of poems in any collection referable to this period and known collectively as the Sangam collection which show this tendency very plainly. We shall examine the most characteristic of Tamil works with a view to this end and see how far there is any Aryan influence traceable in it. Before proceeding to that examination, however, it is worth while pointing out at once that it is acknowledged on all hands by common tradition that the Tamil language originated with Siva and that its grammar was put into systematic form first by Agastya and then by his disciple the author of the Tolkappiyam on the model of the Aindra School of Grammarians. The earliest tradition regarding the emigration of these people exhibits Aryan lead also. It was Agastya that led the emigration. The bulk of the people belonging to the ruling and agricultural classes were led forward by him in a colony from south-western Hindustan, the land of Krishna. It is they that destroyed forests and turned these into arable land; in other words, introduced the first elements of civilization from the north. This tradition no doubt states that Agastya's grammar preceded that of Panini and that the division of the Vedas accepted in the Tamil country is based on the older Sakas, rather than the division into four recognised groups by Vyasa. The only authority extant for all these traditions however, it must be noted, is tradition preserved for us by the commentators of a much later period; and the one that is preserved which offers full details is that preserved by the Brahman commentator Nachchinarkiniyar who lived in the twelfth or the thirteenth century. We are not however dependent upon this late tradition for our authority. We can trace innumerable details in the body of the literature in original that has come down to us, and if these details should be put together it becomes fairly clear that so far as literary Tamil is concerned it is undoubtedly of Aryan character with equally indubitable traces of other than Aryan features in it, features which are far too primitive in comparison.