>>512961845
The answer has two parts:

Judeo christians wrote our "chronology". It is pure shit and larp. You can forget everything up to circa the 2nd millenium CE.
Id est, the last thousand years are only vaguely correct in terms of histories realities, the rest is trash and horribly inflated.

Second, "civilisation" came in spurts.
Most of them amounted to nothing, for example the Maya.
Most cultures going the "civilised" route went extinct thousands of years ago with nothing to show for. The vast majority of tryouts are doomed to fail because
>they must rely on agriculture
this depletes the soil, quickly degenerates the people via malnutrition,
>bad hierarchies and social problems arise
as a consequence of too many people on top of each other. It's difficult to come up with a system to disencourage grifting and stealing. How can you make everybody contribute willingly?
>outer pressure
the non-civilised will simply raid with impunity at some point. Vikings in America were no match for the savage hordes

This means your "civilisation" must have lots of extremely fertile lands to experiment around because the experiment will fail and some semi-permanent state must follow where the knowledge and genes can remain until the next try.
There are only a few spots so forgiving and among these there are
>Egypt, Middle East, Ukraine, Indus Valley, Chinese Heartland