"The Brahmi script reached Upper South India (Andhra-Karnataka regions) and the Tamil country at about the same time during the 3rd century B.C. in the wake of the southern spread of Jainism and Buddhism" Iravatham Mahadevan (2003). Early Tamil Epigraphy from the Earliest Times to the Sixth Century A.D. Cambridge, Harvard University Press.
[1] E. Annamalai, Sanford B. Steever, 'Modern Tamil' in: Sanford B. Steever (ed.) The Dravidian Languages Routledge (1998), 100–128, mention 254 BC as the date of the earliest datable inscription.
