POPULATION

First thing a ruler of the country would love to know is how many people are his subjects, at least aproximately. Otherwise you'd have no clue how much taxes to expect, how many people you can draft, where to station your troops, etc. This is crucial information. So when do you think there was a first national census in France? 1801. There were approximate local records and estimates made since 1600+, there was a census of all North American colonies in 1666 (3,215 people total, estimated 55,000 in 1754). Britain? 1801. Some censuses are claimed in medieval, but not much since(!). Spain? 1785-1787. Yet France organized census in North America in 1666. I can't imagine they failed to do the same in France. They just can't show it.

WHY?

What should the European demographics look like in real world? In much worse climate and harsh living conditions, in Russian Empire, enslaved, hungry and freezing Russian people still managed to breed quite rapidly, thanks to huge territorial gains, population grew from 35,000,000 in 1800 to 125,000,000 in 1897 (more than 3.57 times in less than a century). Russia had famines (1891-1892, 1899), Napoleon's invasion in (1812) and several smaller wars, including multi-decade Caucasian War (1817-1864), and also several cholera epidemics in 1800-1900. Russians kept breeding because in rural environment children are an asset: "free slaves".

If at least agriculture existed in Europe 2000 years ago it should've been overpopulated by medieval, yet famous Malthus book on threat of global overpopulation only appears in 1798. There was no such concern anywhere in Europe before. France and Spain practically gifted their vast territories in North America to USA for that very reason: not enough volunteers to send to colonies. Somehow there was enough free land for everybody in France and Spain, until 1800. Ater the initial influx of protestant refugees from all over Europe run out, Britain, in 1700+ had exactly same problem, which explains American independence: there was simply not enough soldiers and new colonists to send to suppress the rebellion.

Let's take 10,500,000 of 1800 Great Britain population and divide by Russian 3.57 growth rate. We get ~2,941,000 in 1700 , ~823,000 in 1600, ~230,000 in 1500, ~230,000 in 1500, ~64,000 in 1400 ... Spain population in 1800 is same as in Britain(!), France is 26,000,000 (France area is larger too, climate is better, started earlier, included some pre-populated Germanic terriories). During "Hundred Years' War", e.g. in 1400, France total population would have been less than 200,000. Historians claim it was 16,600,000.

HUNDRED YEARS' WAR

I really wonder how they came up with this number since the (obviously exaggerated) "holy sources" of "Hundred Years' War" describe 65 battles in 116 years with average casualties around 5,000. Accounts are pretty detailed: some "battles" involve only few dozens/hundreds people. In a 16+ million country this kind of warfare somehow reduced the population drastically. Unfortunately the contemporaries forgot to mention France population at that moment, and modern historians can't do math.

IMHO "Hundred Years' War" is a glorified tale of France colonisation with some clashes between Italians, Germans, Normans, Semites. The actual warfare started much later, when population became denser and economy picked up. "French" taking Calais in 1558 from "England" is probably the actual end of actual "Hundred Years' War", followed up by repressions, riots, and ethnic cleansing that is described as "Huguenot Wars" (1562-1598).

BRITISH DRAFT LISTS

According to British draft-lists of 1500+ ("muster lists"), armed men from 16 to 60 in "trained bands" numbered 50,000 in 1588 (comprising about a third of the militia) ... 42% firearms, 26% pikes, 18% longbows, and 16% bills. "Bill" is a branch trimmer. The weapon percentages are for the elite 50,000, from which we can safely conclude that ~100,000 not-"trained bands" included pretty much anyone who could walk. Let's multiply total ~150,000 by 2 to account for disabled, old, sick, and children. Double 300,000 once more to include women: ~600,000 in 1588. So my estimate for 1600 made sense. Yet this number is at least 5 times lower than the mainstream 3-4 million estimate. Guess what data they have to claim 3-4 millions? None.

CHILD MORTALITY

You've probably heard them weeping about chiild mortality, but in poor 3rd world country (Georgia) my grandpa's grandpa, a peasant in Russian Empire, raised 10 children with no vaccinations or anabiotics. Amish or Hasidic Jews have 7 children per family on average and at least Amish aren't big fans of vaccinations.

CASTLES

Encastellation is a special historiography term for 800-1200 (link is to Italian wiki since it does mention centuries) when the castles are built all over Europe. Castles are the most basic defense structures. Any buildings dated earlier than this, even in Greece and Italy, are misdated. Official explanation is that around this time Vikings and Saracens started annoying civilized Europeans. Somehow castles weren't in fashion when Germanic tribes and Nomads were doing exactly same centuries ago. Great Roman engeneering just didn't care enough. Roads, aqueducts, amphitheatres were way more important than defense of the Empire.

DENSITY

Stone Age population density is estimated ~ 0.0444-0.1223 people per square kilometer. Area of France is 543,940 square kilometers. Lowest population estimate would be 543,940 * 0.0444 = 24,150 people. That's hunter-gatherer with a club density. Now let's take the 1400 estimate of less than 200,000 and continue dividing it by 3.57. 1300 - less than 60,000. 1200 - less than 20,000.

These numbers mean that France, Spain and Britain lived in Stone Age in 1200, and Italy (17,000,000 in 1800) and Holy Roman Empire (~comparable to France) were there in 900. There were some Phoenician villages colonies spread thin along the coast of Mediterranean and Atlantic. Denser population would inevitably result in trade, urbanization, literacy and stable governments, which we are only starting to see in Germany and Italy after 1400.

LIES

Famous Black Death (1346-1353) is a "plot device" invented to justify very strange European demographics. Explains nothing since one generation would get the numbers back up. Total lack of immunity for the Central Asian decease contradicts official story of nomads invading Europe many times before 1300. Also Jews, Gypsies, crusades and trade. Rats know no borders. Europe is not geographically isolated continent like North America, Europeans should've head same immunity as anybody else in Eurasia.

Another "plot device" is Western European marriage pattern - a unique Western European cultural phenomenon: medieval people with no education, no mass entertainment, loads of free time, massively decided to not marry or marry late. Were they concerned about Global Warming or was it Gender Issues? These rich people from typical family portraits of around 1800 have never heard of such thing as Western European marriage pattern:

Poor people, especially in countryside, marry earlier and breed better. You can google lots of 1800+ European family photos and count children in them. This is not a proof that everybody had many children but a proof that there was no late marriage or less children trend even in crowded Europe of 1900. No woman in her sane mind would risk missing her "prime" age in times when there were no other employment options for women and cosmetics weren't as available as today.

WORLD

World population in 1900 is estimated as 1,600,000,000. If we apply same coefficient 3.57 we get to Stone Age population density for the whole world by ... 1400. This means that most of world population has only been introduced to agriculture recently: India, China, Americas, Africa, were mostly in Stone Age 400 years ago. E.g. if India was overpopulated as long ago as historians claim, it would flood other territories around it, and we do see some of that: gypsies, Indonesia, Nepal, Bangladesh. Seems a lot, but it's only a fraction of India's population. Same about China. In each case a small core mastered agriculture and was breeding and colonising the rest.