This sounds a lot like something I read not that long ago (it was on acoup, of course[1]) about post-Roman population density, how the carrying capacity of the

This sounds a lot like something I read not that long ago (it was on acoup, of course[1]) about post-Roman population density, how the carrying capacity of the Roman Empire was high because of the increased efficiency allowed by having a good transportation - classic economic specialization. But once the Empire collapsed, the specializations it enabled couldn't come back, and it took a thousand years or more for former Roman provinces to return to their Imperial population levels. 1.https://acoup.blog/2022/02/11/collections-rome-decline-and-fall-part-iii-things/ https://acoup.blog/2022/02/11/collections-rome-decline-and-f...