It's more than just a hunch to me. I do believe the real history of humanity here on earth is nearly entirely suppressed, what we are led to believe is just the tip of the iceberg and not even accurate.

I could cite countless examples, I just want to start with this one which I've found very interesting for a long time, the Voynich Manuscript. Can be found here - https://archive.org/details/TheVoynichManuscript

This may not be the best or most verifiable example of an ancient artifact from a previous advanced civlization, I just find something about this one remarkable. This particular copy is believed to have been made around the 1400's. Passed through many different owners throughout the years, all of which were apparently perplexed. In the early 1900's this manuscript narrowly avoided being sold to the Vatican Library, where we would have likely never seen a glimpse of this.

Written in an unknown language, depicting many unknown plants. Other sections illustrating what appear to be some type of astrological diagrams. Nothing much of this entire 200+ page manuscript makes much sense. The entire thing could be a 600 year old joke. However if not, the information within it is likely invaluable. I do believe this is real, there have been too many credible attempts over the centuries to decipher this manuscript, all have failed to my knowledge.

My first impression of this is that it's a copy made several hundred years ago of a far older book from a previous advanced civilization that happened to survive until this copy was made. I still believe this is the case. I get the impression this manuscript explains various plants and their various effects/uses, among other things.

Any thoughts or ideas on this?

I think it's more so that there's much more that we need to re-learn. Something tells me that long ago we were just more than what we are now. We knew more, we did more.

I think even with a simulated reality, there's still definitely a human history here, and that history can go back literally hundreds of thousands of years for all we really know. The illusion is what we are taught to believe in school through mainstream education/elementary science and religious dogma.

With the Voynich manuscript I get the impression it's a manuscript describing various plants that no longer exist and their uses, dating back to the time before the younger dryas period some 15-20,000years ago. I might be in the minority but I do believe we've had quite advanced civilizations tens of thousands of years ago. Most definitely some of these plants could have had entheogenic properties. However, civilization ended and had to start over, with most information being lost.

I don't think the Voynich manuscript was the product of entheogenic hallucinations, although I was just reading about the possibility a lot of religious texts were the product of entheogens and it makes sense to me.

I don't have any personal experiences with things like ayahuasca or peyote, I have only done LSD. I don't think LSD falls under this category because it's more synthetic if I'm not mistaken, but I didn't have any spiritual event, it was just a fun time with colorful visuals and movement. Would do again.

Hypnogogic hallucinations through meditation can be just as strong, or even more strong, and require no mind altering substances. I've experienced this myself, in that half-asleep completely conscious state somewhere between this reality. I think this attributes to a lot of religious visions that have been documented. Whether they have actual meaning, I can't rule that out.