Hello, I am currently working on creating a fantasy map for a D&D campaign I am running. Using lots of other fantasy maps for reference, I have noticed that most maps are predominantly covered in a generic light green color that is supposed to represent either farm land or land that is reasonably farmable. While this looks aesthetically pleasing, I was wondering how accurate it was. When I went to develop my own map, my gut instinct was to have the temperate forest region I was working on be pretty heavily forested with the exception of farm land that was coalesced around towns and cities.
If you zoom in to any light green area on Google Earth, you can see that almost every single possible inch of this planet is being milked for everything it is worth. There are farms quite literally covering every spare region of non-mountainous, non-oceanic, non-heavily forested, non-glacial terrain. For a population of 7 billion, this makes sense. But for a setting based off medieval Europe, does it make sense to have vast stretches of farmland between towns? Hundreds of miles worth?
Here is an album I put together: https://imgur.com/a/BvZhMf8 The first picture is a partial map of Faerun, a common D&D setting. The next few pictures are the Google Earth thing I was talking about. The last two pictures are example maps I whipped up in 5 minutes to highlight the difference between what is the standard, and the way I imagine medieval Europe, respectively.
So, if anyone out there has any knowledge or insight into this, I would love to know how much farm land is an appropriate amount for sustaining a population roughly the size of medieval Europe.
The whole of medieval Europe may be a bit of a stretch, but we can certainly work out some regional minimum estimates from surviving textual evidence.
The Burghal Hidage is a document from c.910-918 in England which lists the hides of land attibutes to each of the West Saxon burhs. Each 'hide' supposedly contributed a man to the garrison, and guarded approximately a 'pole' of wall (about 1.5m in Mercia, slightly shorter in Wessex). The size of a 'hide' is never fully confirmed. By the size of Domesday, it has been standardised at around 120 acres, but could be bigger or much smaller, even around 40-50 acres depending on where in the country it was and how productive the land was. A 'hide' of intensive and fertile arable crops, for example, would be noticably smaller than a hide of sparse sheep grazing.
Exeter in Devon is assigned a hidage of 734, meaning that if we standardise on about 120 acres per hide, this is 88,080 acres, or 137.6 square miles. What that means is that, all land within 6 miles in every direction of Exeter could be in use for the garrison alone. In practice is was likely to be spread over a much wider distance, as the acres within those hides were unlikely to be contiguous, but spread across a variety of furlongs throughout local estates, freeholds and smallholds. Much more land would be used to provide for the rest of the population, and some of this information can be seen in Domesday book as well as in other sources.
By Domesday, a single peasant farmer owning a whole hide - if he wasn't a freeman - was unlikely, and most peasant households whether freemen or 'villeins' were assessed in virgates of approximately 30 acres. Again, these sizes could vary wildly depending on productivity and location. To return to Exeter, the suburb of Polsloe is listed in Domesday as containing 5 households - one smallholder and 4 slaves. A smallholder may own around 5 acres for his own use, and a further 2 'ploughlands' are listed. These are essentially the same as a 'hide' or the oft-used carucate at approximately 120 acres. These 240 acres at Polsloe, therefore, are likely to have been worked by the 4 slave households either on behalf of the old lord (an Ælfric), or post conquest for the canons of St Peter and St Mary in Exeter. Polsloe's land alone, therefore, is about half a mile square, and it is within a mile of the much larger Whipton, which suggests that all of its land was being used for farming.
Whipton, for what its worth, was a larger settlement of 5 villagers, 3 smallholders and 7 slaves (approximately 40-60 people), with 8 ploughlands, of which 6 were cultivated. This provides around 720 acres of land, alongside which were 100 acres of pasture for grazing sheep and cattle, so roughly 1.1 miles square. This brings us neatly to the next village, and so on.
The point of this slightly wandering diatribe is that the the vast majority of land that could be worked, would be worked, and that around major settlements at least, significant areas of majority agriculture could be expected.