[nradov]

I think some people get hung up on the word "advanced". They jump to assumptions about fringe theories about Atlantis or flying saucers or whatever. But in this context, "advanced" just means a slightly higher level of masonry and some metal tools, perhaps comparable to what we now consider the Bronze Age in Eurasia. It's entirely plausible that such a civilization could be entirely wiped out, leaving few artifacts that could last >10K years.

[ncmncm]

The most likely place for such evidence is the sea floor off India and Pakistan, and the bottom of the Persian Gulf (which archaeologists must be careful to call the "Arabian Gulf", in e.g. YT vids of recent work on the area.)

The Harappan cities are overwhelmingly more sophisticated than would be consistent with their being the first of anything. The oldest Harappan cities were exhaustively planned before construction started, with central sewers fed from every house, all carefully graded to maintain reliable flow.

The Harappans must have had writing, but on stuff that crumbled to dust thousands of years ago.

A million square miles of what is now sea floor from Korea to Viet Nam, and south to Java, was rich river-drained bottom land until 20000 years ago, filling in until 8000 years ago. People had lived there for at least 20000 years before the sea began rising.

Also, Australia was connected to New Guinea, and again people had lived there for as long. There are still precise oral records of conflicts and resolutions as the water forced people uphill to where other people already lived.

There is a very large construction on Java, Gunung Padang, that had been thought to be a natural hill, but it has turned out was built at least 20000 years ago. (Some think a natural hill must be inside, but we really have no idea.)