Well how far back are we talking? 200,000 years or just since writing was invented. Technically those cave paintings from tens of thousands of years ago could be telling historic events of some kind but if we even just say “only since 5000BCE” and only consider events of significant historic consequence shaping any given region (as opposed to neighbors starting a blood fued by shitting in each others yurts), then it’s STILL probably like 90% lost which is just wild.