I think pseudo-science is a good place to discuss this. There is limited evidence that some technologically advanced (for the ancient age) societies might have developed during the last ice age, before it ended about 10,000 years ago, mostly in areas now covered by ocean.
We're not going to get really good archeology on those places any time soon, because you have to dive to even reach the ruins themselves, but it's probably where you'd have to go to find the evidence, because they'd be the only warm places back then.
Some people think the Great Pyramid and/or Stone Henge could originate in an older era. Most of the places that are suspected to have harbored advancement are concentrated around the equator, or near it. The meditaranian sea, some of the waters south of India, some of the Gulf of Mexico, and .... of course.......... a mythical land mass that may have once collapsed to form an underwater plateau around the Azores Islands in the Atlantic.....