I watched this video and now I am curious. They show the population of the world 1000 years ago and they also have a population distribution map. How do you estimate something like that? And is the distribution map just a guess or is there some reasoning involved? And if I were to do something similar with my country's data where would you suggest I start?
My understanding is typically:
- For hunters & gatherers, and pastoralists, population density is assumed to fall within a known range for such peoples today.
- For farming societies, their large cities can be estimated(pdf) based on the (geographic) size and habitation density. Their smaller towns can be estimated similarly, and then the total population of those estimated based on the known density of such towns.
- Some ancient societies actually produced Censuses for their own (usually military and/or taxation) purposes. For example, we know from a 6th Century BCE census that the Kingdom (City) of Rome had 80,000 men of military age. Adding a small percentage for those out of that age, then doubling that to count the women shouldn't get you too far off its actual population.