Put it simply, the coast line of India , more specifically Tamils extended up to Equator.
And this tallies with the descriptions of Tamil Kings in The Mahabharata during the Swayamvar of Draupadi , the reference to Arjuna having married the daughter of a Pandyan King and the mention of Cheran Perunchotruudiyan Neduncheraathan as having fed both the armies of the Panadavas and Kauravas during the Mahabharata War, among other refernces like the Tamil Knings donated Villages for Baramins po perform Vedic Rites daily in the Agraharas, ear marked for them.