Interesting that even in ancient Tamil populations there was a theory around cities and lands lost to seas.

It may well be true when you consider they might be talking if the world as it was during the last Ice Age – a mere 16,000 years ago (as opposed to hundreds of millions of years ago).

A map of the world as it was during that time is below (thanks to https://www.ngdc.noaa.gov/mgg/topo/data/pictures/?C=N;O=D)

Tamil Lands would have included the India-Sri Lanka bridge, and a much greater Coast to the west of modern Kerala. All of which have since been “lost to the sea”.