Your claim that Kannada wass used to form Tamil only evokes laughter as there are no proofs for it. Tamil is not 2000 years old but certainly a long way before that. Tholkappium, the oldest surving Tamil literature(Indian in records) date between 500 B.C to 200 B.C. It belongs only to the second Sangam and it provides references to a large number of literature existed before that but eventually destroyed. Morover, Adichanallur inscriptions date to 600 B.C where it talks of a land dealing between the landlord and a customer and the kind of trade between them. Earliest Tamil literature like Silappadhikaram also speaks of Kumari Kandam where the first Sangam held and the subsequent flooding by sea. This Kumari kandam is a submerged landmass in Indian Ocean which connected the south India with West Australia. This is proved by the theory of Plate Tectonics. There are much more evidences like this.
