The existence of man is set by mainstream science at around 200,000 years.
With half of that time frame, taking the mainstream yardstick for modern civilization at 5,000 years starting from the start of writing in Sumeria at 3,000 B.C.E, that allows for at least 15-20 possible civilizations to exist in one region alone for the rest of the 95,000 years before that.
Even if the yardstick of developing modern civilization to what it is today is set at 10,000 years, that still leaves another 9-10 possible civilization timelines to exist, again not counting concurrent civilizations in other parts of the world concurrent to the given area.
This does not count concurrent civilizations that might exist in other regions.
The challenge to this assumption is the evidence, or the lack of it.
The problem is few things can last beyond a thousand years, even fewer can last beyond 5,000 years, except giant stone structures like Stonehenge and the Pyramids around the world that makes it obvious they were not placed there by Nature.
And then there's the active censorship at work by the mainstream academia who believe they have a monopoly on knowledge, or have been trained to think in such a way that ensures they put out the mainstream narrative.
The idea that we waited until 5,000 years ago and then through this one civilization 'invented' everything with writing, the wheel, the first city center and urban settlement as well as economics, money and inventory in a short span of time is a hard one to accept.
These guys were very likely rebuilding civilization with the knowledge they already have, acquired elsewhere. Where is that elsewhere is unknown, but this wasn't the first time.