Originally Posted by Infernally Clay
The fall of the Jedi at the hands of the Sith and the fall of the Sith at the hands of the Jedi both happened within Baylan's lifetime. Nothing suggests he's wrong about this cycle or that it doesn't exist.

…He'd know better than us if the galaxy used to change hands every thousand years or if it has done so with some frequency.
Absolutely this. Baylan may be waxing poetic at some points, but he’s certainly the most contemplative, historically-minded antagonist we’ve seen in Star Wars so far, and there’s no reason to believe his understanding of galactic history isn’t essentially accurate.

Originally Posted by Infernally Clay
Twenty five thousand years ago mammoths still walked the earth and we lived in huts made of rocks.
Mammoths yes, rocks not always. Gravettian dwellings from this timeframe were often carefully constructed of mammoth bones overlaid with hides and furs, and it seems some huts had artistic patterns worked into the arrangement of the bones.

An excellent reconstruction of this type of mammoth-bone settlement can be seen in the movie Alpha (2018), although sadly the rest of the movie isn’t quite so historical.

Originally Posted by Infernally Clay
The Galactic Republic has existed for twenty five thousand years, which means digital records have existed for much longer. Everything would have been catalogued. The entire lifespan of civilisations and cultures would be stored and recorded somewhere….
The basic point is well-taken, but we shouldn’t assume that records from the early days of the Republic are automatically accessible, or anything more than digital static with a smattering of recoverable scraps.

I have stacks of 3.5” floppies I can’t access because I can’t find an external drive that isn’t cheap crud. I have old family movies stored on reels I can’t watch because I don’t have a working film projector. That’s in just a matter of decades: imagine the changes in format and technological turnover that must have occurred across tens of thousands of years. Even assuming the Republic eventually settled on a standard format, they probably have thousands of years of information stored on their equivalent of Betamax, or cassette tapes only readable by a TRS-80.

And digital archives aren’t immune to degradation across those timeframes, to say nothing of deliberate attacks. I could see a superweapon designed to cause a star to emit massive solar flares to wipe out all data storage in a centralized location, both as a psychological strike in itself and as a way of eliminating knowledge of all manner of things—histories, technologies, entire cultures and species erased. The opportunities for villainy would be virtually limitless.