Just how much of our Ancient History do we actually know? (1 Viewer)

[FragiLimbel]

Say from like 2000BC; Do we know every single major event that has happened since then, or is there a chance that we still haven't uncovered some evidence showing mass migrations or major battles between empires. I know the specific details of these events aren't fully known, but do we basically know of all the main events that have occurred? For example, the Exodus. With all that we know of that period, is it now factual that Egypt did not have millions of Jewish slaves and that there is no way they migrated en masse?
Another example. Is there a chance that we may discover a brutal massacre by Alexander the Great whereby he slaughters 50 000 people or some shit like that?
Basically, anything that would have obviously left a trace, have we discovered all these traces from our Ancient world?