My wife and I have recently been rewatching a number of movies set in analogues of medieval Europe, movies such as 1982's The Last Unicorn and The Dark Crystal and 1988's Willow. As we watched the last, the thought occurred to me that there appears to be a trope of setting among them, a trope seen in Peter Jackson's Lord of the Rings and Hobbit films, as well, and in others I could name but have not watched recently enough to discuss. In each, the populations appear to be quite low to sustain the military forces seen; there do not appear to be enough people to feed all of the fighting folk, and there seems not to be enough housing to hold them all in the structures that are in place. (For the most part; there are, of course, individual exceptions within each milieu.)
I have to wonder if the persistence of medievalist milieu as largely empty has to do with a concept of the European Middle Ages as really being after the Black Death, when much of the population of Europe had succumbed to disease. David Whitton notes in his contribution to The Oxford History of Medieval Europe, "The Society of Northern Europe in the High Middle Ages, 900-1200," that forests were cleared, marginal agricultural land put into production, and the sea driven back to make room for a burgeoning population, and trade among the various people increased greatly during the period. For some of the European medieval, at least, there were more people about than films that echo or try to recreate the broader concept of the time display. Military technologies tend to be more advanced than to fall before the High Middle Ages; Willow, for instance, shows a number of weapons that smack of the later Middle Ages (not to mention an interesting combination of mail and plate on Madmartigan), and Lord of the Rings features gunpowder at Helm's Deep. Thus, such films appear to work from a view of the medieval as following the Black Death.
I am aware that Tolkien's mythic history accounts for a plague. I am also aware that following Tolkien is a thing to do. So perhaps that is part of the why such choices are made. And part also is the need to keep costs in line--and populating a place requires people, who must be paid. (Or, more recently, CGI artists, who must be paid.) But it is telling even so that the vision of the medieval/ist as taking place in a depopulated world is one that persists with abundant cultural force. It surely says something about the expected audience that the trope would continue as it does in major multimedia projects that attract significant attention from mainstream audiences. Perhaps it points to an assumption of feelings of isolation among the expected audience, and while many people feel cut off from others at various times, it must be considered that stereotypes of certain populations perceived as enjoying the medieval/ist are at play. Perhaps it points to other things entirely. But it points to something in enduring, and teasing out what it signifies that medieval/ist works tend to feature milieus of low population density would be worthwhile.