History VIII: The Long Arm of the State

How far does influence extend?

As empires grow large, it becomes difficult to control the extremities. Eventually, it collapses under its own weight. There are several mechanisms to describe this, but first I'll concentrate on the physical size of the hegemony.

As of the last running of my history simulator, the largest hegemony (Drudny) covers 785 cities. It's massive, and contains a huge number of people (around 64M) when both rural and urban populations are considered. For comparison, the zenith of the Roman Empire had around 90M people and the equivalent of about 5500 cities/hexes of area. Based on that, I think my population equation is somewhat skewed.

An empire of this physical distribution would be nearly impossible to maintain given the restraints of the fantasy-tech level, where technology and travel are severely limited and magic is rare. The degree of control that the capital city $i$ has on a given city $j$ located $\delta_{ij}$ days away (not necessarily the straight line distance) can be quantified by the following metric: \[C_{ij} = {P_i \over \delta_{ij} ^ n}\], where $n$ is the distance modifier, usually 2. Values for the Drudny hegemony range from 32531.15 (right next to the capital) to 11.32 (over a month's travel away).

How much of a "rebellion index" does this number represent? It's difficult to say. The best way forward for now is to fix a number and test it out. A Monte-Carlo by fire. A city with $C_{ij} \leq 25$ is susceptible (not automatically!) to revolution. A value of 25 means that a city of 1000 can reliably control hexes up to 6 days away, and a city of 25,000, about 30 days. For these threshold cities, the chance of revolution each year is 25%, which would lead to a revolution within 25 years max if the situation is not resolved.

This obviously leads to the conclusion (as many empires reached throughout real history), that a massive empire is best controlled with some measure of decentralization. China solidified itself with jùn and xiàn; Russia with oblasts; Rome with provinces; Wales, with cantrefi. This decentralization would ensure that every city maintained the threshold score. I will need to think more about how to implement this later.

So far I have not had any empires grow large enough to experience a revolt.