Earlier quoted context omitted.
I don't get that impression. The cities listed fall into two required criteria: documented history and civilization. This does not account for neolithic settlements of which some grew quite large for their respective lack of centralized management. This is qualified by the list mentions some cities were neolithic settlements before they qualified for the status of "city" and some cities existed far earlier than the h…
I think if you downgrade the definition of city to any grouping of animal skin tents, then the entire exercise loses meaning because those were everywhere.
It's interesting that the biggest cities plateaued at about 1 million from about 100 BCE to 1800 CE, until the industrial revolution kicked in.