A City's Elite

And Some Mercantile Math

The core principle of “top-down, zoom-in” world design is that we only need as much detail in a given region as will have an actual impact on gameplay. Based on that principle, I have detailed out the realms on my regional map where my Shattered Lands campaign is set, but the grand kingdoms to either side I’ve left abstracted with only a general sense of their population and extent.

However, as my players are interacting more with those “off-screen” kingdoms, they increase the influence of those realms on the campaign, and before long they’ll be making war with or against them, and this demands a more detailed approach to them. ACKS does give me the tools to take a simple estimate and just use that, but I think there’s a lot of value to be had in leaning into the realm-level differences we can see there — to the west, the broken empire of Telemnia, with a bunch of senatorial domains mixed between the more “standard” grants of nobility, and a set of imperial governorships with land ownership partially divorced from local rule. To the east, that manifests in the mercantile oligarchs of the Madran League, with the largest realms managed by senates/oligarchies and the smaller domains generally being freeholds.

One consequence of that in turn is that I’m looking to estimate the wealth of an established merchant class within a given domain/realm, in order to know what proportion of a settlement’s elites might be involved in trade. We know that a Class II market of 10k families yields 20kgp per month in trade income to the ruler, so I’ll use that as my core benchmark to estimate the overall extent of trade. From here on, the post is somewhat math-heavy, but I thought it useful to share as a big picture example of how I would use mathematical frameworks to translate rulebook abstractions into gameable content.

Quantifying Trade

As a first attempt, I’ll look to the availability of merchandise in that Class II market, and assume that 10x the base merchandise availability gets transacted in each type of merchandise for 30 days in a month (the maximum quantity of transactions, which will give us a hard upper bound). I will assume that half of the goods exchanged via arbitrage are locally produced and thus not subject to tariffs. That totals to:

• 24,531 stone of goods per day, for a total value of tolls of 1472gp at 0.2cp/stone over a 30 day month.

• 25,712gp of common goods per day, with half of that subject to tariffs, with tariffs charged at a 5% rate for a total tariff on common goods of 19,284gp over a 30 day month.

• 58,370gp of precious goods per day, with half of that subject to tariffs, with tariffs charged at a 20% rate for a total tariff on precious goods of 175,110gp over a 30 day month.

All together, that yields a monthly income of 195,866gp to the ruler — an order of magnitude above the real value. I could pretty effectively solve things by just reducing the initial assumption from 10x the base quantity of goods per month (the maximum quantity) to only 1x that base base quantity, but before I accept that, I want to adjust the numbers a bit more and see if a more nuanced solution presents itself.

Of the income above, the great bulk is in tariffs on precious goods; it makes sense that common goods may well be transacted in at higher rates than precious goods, particularly given high tariffs. If we adjust the above assumptions to 7x the base availability of common goods, and only 1x the base availability of precious goods, we get a much more reasonable breakdown of:

• 18,151 stone of goods per day, at a 0.2cp/stone toll, for a total value of tolls of 1089gp over a 30 day month.

• 8999gp of common goods per day, at a 5% tariff, for a total value of common good tariffs of 13,499gp over a 30 day month.

• 2918gp of precious goods per day, at a 20% tariff, for a total value of precious good tariffs of 17511gp over a 30 day month.

This revised estimate totals to 32,099gp, which is still 12,099gp too high relative to the ruler’s income. But there’s another potentially important factor we’ve neglected thus far — smuggling! Smuggling permits trade without paying those fees, but how much smuggling actually goes on in a given city? Using my rules for Spy Rings, we can predict there will be 50 rings active in a Class II city, and that a given ring can smuggle 12,000gp of goods per month. With ten major specialties for such rings, we can then further estimate that ~5 rings each month will smuggle goods, for a total value of 60,000gp in transactions that don’t pay tolls or tariffs.

Using a weighted average of prices per stone by good, I get an average of 126gp/stone, so that 60,000gp reduction in transactions is reflected by a decrease in 476 stone of transactions. Taken all together, those factors reduce the ruler’s estimated income from the above volume of trade to 20,098gp — still slightly high, but within a 0.5% margin of error, which is acceptable for my purposes.

Tallying the Traders

This in turn gets me the number I was initially looking for: the gross volume of trade in a typical Class II city is about 715,072gp per month. Breaking that out into common and precious goods, and applying reasonable profit margins to each (44% and 25%, respectively), I get an estimated monthly profit of 281,361gp. Comparing that to the expected monthly wages of levelled characters, and assuming that about 66% of such trade wealth is concentrated in the upper echelons of society (a reasonable guess too involved to fully explain here), I can conclude that, as a rough upper bound, such a settlement could potentially support one merchant at 12th level, two at 11th, three at 10th, and four at 9th level, purely off of trade income.

Comparing to my more general interpolation of settlement demographics, we might expect the settlement to contain one character of 13th level, two at each of 11th and 12th, three at 10th, and four at 9th, so my estimate on the whole seems high but reasonable. I won’t assume that all such characters levelling from arbitrage are venturers, but many of them could be. One noteworthy conclusion of the above is that I’m not likely to see more than one 12th+ level venturer in the city with Monopoly Power, so that particular individual will be quite a force to be reckoned with.

To add a further caveat to my results, the above analysis also neglects potential monopolies in general, and the option for the local ruler to waive certain transaction fees. What I’ve tended to observe in play is that arbitrage in common goods is most popular in the early mid-levels, but that the comparatively low total value of such transactions (even with higher margins relative to precious goods) tends to make them increasingly less attractive as levels rise (because campaign XP thresholds also rise, and the low total value of common goods stops being enough to earn XP off of them). However, just as that shift really sinks in, characters are securing their own domains, in which they can waive tolls and tariffs on their own transactions (and potentially grant themselves a monopoly in a desired good), and trade in precious goods suddenly becomes far more attractive. So to conclude that trade in precious goods is higher than I estimate above, but largely untaxed due to internal corruption, and with its profits accruing to the local ruler and his clients, seems a very reasonable addendum.

Applied Demography of Heroism

On the whole then, what can I conclude about the levelled characters of this city? At the top, we have the city’s ruler (fighter 13), supported by the city and surrounding lands directly (while I’ve called him an “oligarch”, I tentatively think a bureaucratic senatorial realm better fits my vision mechanically).

Below him at 12th level, we have a merchant prince (venturer 12), and one other, either a high priest or a prince of thieves. Using the JJ Realms and Settlements chapters to estimate the domain size, and the RR Campaigns chapter for the divine power and campaign XP threshold rules, I can conclude that the expected monthly divine power in the settlement is around 36,000gp, enough to support an 11th but not 12th level priest; meanwhile, the expected guild income for a prince of thieves is 75,000gp, plenty enough to reach 12th level. So the highest level thief (or perhaps an assassin would be a more thematic fit here?) is at 12th level, and the highest level divine caster at 11th (a priestess of Aliya). That leaves one other 11th level character, supported by mercantile income, so a good opportunity to include a fighter or explorer — I’ll go with the explorer, a renowned fleet admiral.

At 10th level, we’ll include a mage in the ruler’s retinue as his vizier, a crusader of Jash, and a mercenary general, the latter two involved in arbitrage on the side. (As an aside, we know there’s a mercenary general because a venturer could hire him on the Hireling (Specialist) Availability by Market Class table, but we also know he probably has another income source because a non-venturer wouldn’t be able to find and hire him.)

At 9th level, we’ll have a venturer as the formal head of the Merchant’s Guildhouse (which position could go to the 12th level monopolist above, but I like the idea of him wielding power more discreetly, and the value of the guildhouse’s vault per the JJ Settlements chapter is a good fit for the net worth of a 9th level character per the JJ NPCs chapter). Another fighter, explorer, thief, and priest finish making up those numbers for 9th level characters nicely — the fighter in the ruler’s retinue as his elderly Captain of the Guard (and wealthy patron of merchants), the explorer as the eastern grandmaster of the Band of the Red Spear (a martial and huntsman’s brotherhood) and a well-travelled and wealthy engager in arbitrage, the thief as a spymaster to the High Priestess of Aliya, the priest as the presiding Crusader of Elion.

I will keep going, probably down to 7th level, but this seems sufficient as an example of the process. And one can very easily see how, while some positions are effectively mandated by the structure, shuffling around some of the more flexible roles could easily lend the settlement a very different composition (and downstream of that, a very different feel). If I really wanted to, the math suggests I could have even more of the above characters be supported by arbitrage, but the estimate I built above for characters arbitrage could support was an upper bound and I think the present arrangement is tentatively fine (and having room to adjust it upwards later, as I put more concrete numbers to things, is far from a bad thing itself — I may well end up increasing the population of that city, with a correspondingly higher incidence of levelled characters, but negligible impact on the expected volume of trade due to the way it’s modelled).

Is all this really necessary? Not at all, but I enjoy it, and I do think it has benefits. This is the first step in building up a really robust set of factions, and in fleshing out a city to have interesting and dynamic political scenarios (or in knowing who turns out to lead the defense if the city were attacked). If someone seeks healing, or wants to know if they’re the highest ranked priest of a given order, I need details on the local priesthoods; if a PC master-thief wants to start a turf war and carve out a place in the city’s underworld, likewise. When we understand these high level NPCs as the “monsters” of high level political action, we understand that having a concrete sense of their assets and abilities is necessary to run a fair sandbox, just like we would detail the assets and abilities of monsters in a dungeon. PCs might kill them, or outmaneuver them, or ally with them, or do things wholly unexpected; therein lies the game.