Low-Tech Kingdom Population Density?

[Polydamas]

Originally Posted by Sunrunners_Fire

I have a low-tech fantasy kingdom, isolated from the rest of the world due to accidents of geography, history and magic. It is intended to be self-sufficient at TL 4~ and so can thereby be assumed to have a minimum population of 700,000 using the numbers on (GURPS Space, pg 91) as a guideline. The available geography for said kingdom is 3,472 square miles of arable land. With a minimum population of 700,000, this gives a minimum population density of 202~.

I personally suspect that the population required to maintain TL 4 in isolation is in the tens of millions (see: Hellenistic/Roman Mediterranean, Tokugawa Japan). You can have towns and muskets with a much smaller population, but not amazing art and huge libraries and cities with hundreds of thousands of people and pocket multitools and large amounts of good steel armour and all kinds of specialists and ships of a thousand tuns burden. So you will need much more land, or a lower TL.

To give an idea, 700,000 people is one large TL 4 city like Ptolemaic Alexandria, imperial Rome, Queen Anne's London, Tokugawa Tokyo, or any of several Chinese capitals.