OSR: Fast Mapping: Part 1, Kingdom -> County Level

There are plenty of systems for doing this kind of thing properly. Pendragon is great. ACKs is good too. Here's my fast and easy version. It's more of an art than a science, but it does work, and it's very quick. 

Fast Kingdom Mapping

Step 1: Counties
You'll need a map of your setting. Pick the area most of the game will take place in. Put borders around each country (if there are multiple countries). Put a hex grid over your map. I'm using 18 mile hexes (so each hex fits 3x 6 mile hexes. Yes, that does make it a little messy, but for our purposes, it's fine). The entire nation you have enclosed is the Kingdom. If the kingdom is very large it might not all fit on the same map. That's fine. The map below is a subsection of one kingdom (so the borders are offscreen)

Step 2: Major Rivers, Cities, and Towns
Mark any major rivers too large to cross on horseback, even at a ford. Also mark any other impassible terrain in your setting (mountain hexes, lava flows, etc.) Put a dot somewhere in a hex for each major city, fortress, or town (population >5000). There shouldn't be too many. Put some of them along rivers and some of them in the plains. Don't worry too much about logic. Make sure they are at least 1x 18 mile hex apart. 2x or more is ideal.

Step 3: Core Regions
Mark the 7 hexes surrounding some of these major cities/fortresses. Don't mark all of them, but 1/2 to 3/4 should work. If you encounter a river or a border or impassible terrain, stop. These are the "core" regions of the county or duchy, the richest, most prosperous, and most fertile areas.

Side note: you can use this system to simultaneously generate borders and terrain. Isn't that nifty?

On the map below, you can see that the "yellow" county stops at the sea, both "purple" counties stop at rivers, but the "orange" county, one that I wanted to be a major player, crosses the river. You can break your own rules.

Step 4: Developed Regions
One by one, select a county or duchy. Pick the ones you want to be largest first. Working clockwise from the top hex, roll a d6. Draw an arrow in that direction and mark the hex it lands in as a "developed" area. Keep moving and marking hexes. If you run into a hex that's already marked, stop. You can cross rivers and mountains but not national borders.

This step might take a while, but it should produce lovely blobby counties and duchies with lots of interesting and strange shapes.

Step 5: Minor Counties
If any major cities, towns, or fortresses are not allocated to an existing county or duchy, mark the central hex with a "core" marker and all adjacent hexes that are not currently occupied with "developed" markers.

Step 6: Enclaves and Undeveloped Regions
Check to see if any hexes meet these criteria:
1. Completely surrounded on all sides by other duchies or counties.
2. Only one or two hexes (anything larger is dealt with below)

If you do, mark them as "undeveloped" with the nearest adjacent non-bordering colour. These are enclaves of another county that were fully enclosed during some ancient war or complex inheritance. Alternatively, they can represent really minor provinces, royal allocations, elf kingdoms, enclaves of neighboring nations, papal fiefs, or anything else interesting to you.

If more than two hexes are enclosed, follow the "Undeveloped Regions" rules below.

1. If an empty hex has only one duchy or county bordering it, mark it as an "undeveloped region" of that county or duchy. Work your way around the border.
2. If an empty hex has is bordered by multiple duchies or counties, assign a number to each of the adjacent hexes and roll a d6 (rerolling blanks). Mark the hex with the colour rolled.

Step 7: Finishing Touches
After assigning the "undeveloped regions" above, there still might be a few blank hexes in areas between to duchies or counties. You can
a) mark these as "wasteland" or "forest" or "cursed lands" depending on your setting
or
b) repeating the rules in Step 6, assign them as "undeveloped regions". This is the method I chose.

Step 8: Done!
You now have a map of your kingdom. Hooray! Let's see how our version compares to a historical one:

Not too shabby!

Land and Prosperity

You now know which areas are prosperous and which are not. That's very useful information when assigning landscape types, trade routes, or anything else you'd be interested in doing while worldbuilding. Personally, I'd make it up as needed.

Naming

Duchies are typically:
1) large, important, border fiefs
2) granted by the royal family to other members of the royal family, usually to a heir

Counties are typically:
1) large, important, central provinces
2) ruled by hereditary lords

Here are some fake county or duchy names.

Roll	French-ish	English-ish	Scottish-ish
1	Beret	Angled	Colness
2	Lyonal	Longwall	Northerland
3	Aufair	Middlemarch	Scute
4	Pellamy	Thropsford	Underness
5	Entrou	Bunt	Nape
6	Martel	Hapsin	Forscan
7	Alsouice	Underland	Peth
8	Routillion	Overland	Renton
9	Campair	Bell	Kalross
10	Marne	Rent	Rickfries
11	Douvet	Scabes	Selton
12	Nebers	Bant	Borling
13	Prolliance	Lopsterset	Abalness
14	Antrant	Esterland	Olgan
15	Tiers	Scobie	Kenark
16	Fintery	Warton	Moss
17	Boutonnais	Halford	Linith
18	Chervache	Denby	Gowse
19	Guylionne	Bugleham	Winton
20	Saintalle	Holf	Balth