If you read the reports of the early Spanish explorers the American continents had a goodly sized population, the Anastazi were driven out by climate change, for example, small pox did a number on the rest.
East Africa, the Nile basin, and the area below Lake Chad down to Angola had a fair population. the Middle East, Asia Minor, Iraq and Afganistan. were heavily populated. Climate changes have converted some areas that were inhabitable to areas that are uninhabitable.
How about some NUMBERS? Those descriptors tell nothing.