Hi SS, the dates go back to 10,000 years or more in the past.

Check virajendra's first post that mentions the several literary references for kumarikandam, particularly the reference to the sinking of a mahendra malai south of Lanka.

Jayakaran contends the submersion of the land (of several hundred miles) including the strip connecting India and SL, may have happened within the 10,000 years. And that is what is possibly being recalled as Kumarikandam by the poets.

btw his interpretations have also been criticized by people like Kumari maindhan, who maintain that there was no exaggeration and that the submerged land was indeed huge and stretched from Madagascar to Australia, had a flourishing mature civilization.