Sounds like this joker simply wants to replace the official fairy stories with his own. Respected historians, i.e. those employing academic rigour rather than working to a political agenda agree that there is no reliable information on which to base an estimate of pre - Columbian population in the America's. And figures used for European populations around 1500 AD do not include The Russian Empire and tThe Ottoman Empire, which together took in a very latge chunk of geographical Europe.
And is anybody really dim enough to believe black people were once in control of Mississippi. That's as daft as the European lefties who have claimed Beethoven, Van Goch and Einstein were all Africans and most modern technology was developed in Africa and stolen by white colonialists.
If this stuff was from the script of a Monty Python's Flying Circus script we'd still be laughing at it 50 years later.