Before we knew about plate tectonics, a zoologist proposed a lost continent connecting Madagascar and India across the Indian Ocean. That hypothesis, now debunked, was nevertheless picked up by Theosophists and Tamil revivalists.

Lemurs are native to Madagascar. But fossils of lemur ancestors have been found in both Madagascar and India. This is not a puzzle if you know about plate tectonics: Madagascar and India were part of the same continent when those fossils were alive. However, for 19th century English zoologist Philip Sclater, it was most confusing.
Sclater saw the fossil similarities between India and Madagascar and came up with an insightful – but completely wrong – hypothesis. The two lands must have once been joined together with a landmass of some kind. And, at some point in pre-history, that land bridge must have sunk beneath the ocean’s surface like the mythical Atlantis. In honour of the lemur fossils that set off this idea, he coined the name “Lemuria.”
The scientific conception of Lemuria died when plate tectonics gave us a more elegant explanation for those fossil similarities. But the idea of a lost land underneath the Indian Ocean persisted. Theosophy, that fringe religion founded by 19th century occultist Helena Blavatsky, latched onto Lemuria. In theosophical teachings, this lost continent was the home of the third stage of humanity’s evolution. Atlantis was the home of the fourth stage, we are the fifth, and some day soon we’ll be superseded by a sixth and eventually seventh.
The theosophists weren’t the only ones interested in an Indian Ocean continent. The late 19th century saw a revival of Tamil culture as distinct from Indo-Aryan; this was fueled by the exploration of ancient Tamil archaeological sites and the rediscovery of classical Tamil literature. And a cornerstone of that Tamil tradition was about to collide with the idea of Lemuria.
According to Tamil tradition, their great works of literature were produced by a convocation of poets and scholars, the so-called sangams. The first sangam lasted for four and a half thousand years. At that point, the city hosting the sangam was destroyed by the sea. The second great sangam lasted less than four thousand years before it too fell beneath the ocean’s waves. The third sangam was held in Madurai, now the capital city of Tamil Nadu in southern India. It, fortunately, did not sink into the ocean:

Some Tamil revivalists made an explicit connection between these lost sangams and Lemuria. Lemuria was a lost continent named Kumari Kandam. It was a huge triangle of land that stretched from Africa to India to Australia. It was home to the first two sangams and the ultimate homeland for the Tamil people. This idea was so popular that in the 20th century it even made its way into school and university textbooks in southern India. Kumari Kandam was the Atlantis of the Indian Ocean.