for h in hexes:: Agriculture

I have long been fascinated by the Worlds: History project. Go check it out.

One idea I'd like to ~~steal~~ gain inspiration from is the discovery system. People groups have chances to learn new technologies over time (or even lose them). It's quite comprehensive in design if not fully filled out.

I love this. Conceptually, it should synthesize with my existing tech tree, yielding at least the following benefits:

Prehistory is now possible; Year 0 doesn't necessarily start with the first city, and every polity doesn't begin with a city/settlement.
Tribes/polities should be able to migrate more rapidly, reaching more area of the planet's surface.
Technology will be different in different areas. This already exists but is fairly deterministic, based on population density. If your density is X, then you have agriculture, for example. This is captured by the tech level.

The downsides? It's a whole 'nother branch of work for me in addition to all of the research I'm already doing. So it might be useful to build it as a toggled mod. Additionally, DrTardigrade is working on timescales many factors larger than mine.

As far as agriculture goes, there is no better resource I've found for implementing crop distribution than the Ramankutty Lab. This is an absolutely fantastic repository for the distribution of 175 different crops.

However, that's a lot of work for me to do, even though the heavy lifting has already been done. I have to figure out how to translate those stats into something my program can read. I have climate data, of course. Just have to decide which wires to plug in where.

Ramankutty provides some models for predicting crop cultivation based on the length of the growing season. This is a good start, although they use some data I don't have, like the actual evapotranspiration and the soil moisture index.

For my purposes, at first, I might just go through the data and figure out what Koppen climate the crops roughly align with. That's easy enough to do by layering the kml files which are easily available. I'll only post an example here: please go over to the repo linked above to get the data for yourself. It's very informative. This is probably the easiest way to do it: I can't find any crop lists compared to Koppen unfortunately; there are some broad generalizations but that's all.

Source: Earthstat

Then again, it'll take a long time to go through 175 crop types. So I think I'll prioritize and work through them here and there. I'm also having a lot of fun making the symbols for them. I've either used alchemy symbols straight from the Quivira font or combined glyph shapes in Inkscape to maintain a consistent style. I also like the Symbola and Esoterik fonts, but I haven't had occasion to use them yet. I don't always use the alchemy symbol, most for metals, but I do try and tie it in somehow if I can. If a bunch of mystic medievalists did all the work for me, why reinvent the wheel? For example, barley and rye (both used in alcohol production) use various forms of alcohol symbols.

In terms of translating the yield numbers to actual reference numbers, we can calculate the number of acres it takes to produce one reference, and we also need to know the amount of arable land that's available for agriculture. This varies from climate to climate, and I need to do a more detailed study of the percentages there. For instance, India's Aw climate gives them a mind-boggling 52% of arable land, but only 4% is used for crops. Then, how many people does it take to work a single acre? Estimates are all over the place (since it may vary per crop), but the basic grains seem to be around 20 acres a person. I'd rather use 10 in the absence of better data for now. I've worked 10 acres before (vineyard), and it was rough but doable.

So the code will need to decide if the settlement will run out of available hands or available land first. Not so hard.

I'm looking over these yield numbers and some seem a little high for a pre-modern society, even assuming some magical assistance from the local druid. So I may revisit them.

Wheat: Cfb. Primarily, at least. One thing I'm doing is ignoring some of the smaller yield areas to account for differences in technology. Wheat is pretty hardy and can be grown in many different climates, but the highest yields are predominately Cfb. Yields 1,000 lbs/acre.

Barley: Cfb, Cfa, BSh, Dfb, Dfa. Another versatile crop, without which your stereotypical dwarfs will be ale-less. Of course, if you want beer, you need hops as well. Yields 100 lb/acre.