Low-Tech Kingdom Population Density?

[gjc8]

Originally Posted by Polydamas

So let's look at your example of the British Isles in 1450 suddenly being cut off from the continent...

You make a much stronger case that innovation stops or significantly slows down than that there's significant technological backsliding. Many of the things you mention are about stuff that's being invented, discovered, or developed elsewhere, and then never reaching an isolated England. But there's a difference between that and losing access to technology that's already present.

Which, it seems to me, is consistent with what actually happened in Edo period Japan, although they didn't cut off all foreign trade, and they did seem to have a significantly higher population (estimates seem to be 20 million-ish in 1650).