Speaking of Malkioni, their two big empires are Seshnela and Loskalm. Both are about a third the population of the Lunar Empire (Loskalm a little more, Seshnela a little less). But their state resources are significantly less than a third of the Lunar Empire.
A big part of the reason is the different social structure. Legally or ideologically, the King of Seshnela does not “own” Seshnela. He is the head of the talar clans that rules Rindland, Tanisor, Deu, and Voi. Various other talar clans rule other areas, and they owe service and fealty to the king. Moreover, within the areas he rules, many subareas have their own talar families that rule and owe service and fealty to the king.
Pretty quickly it becomes apparent that the king has to rely upon the service and fealty owed to him by his subordinates to do anything. He’s like a mafia chief heading up a crime family – he relies upon his caporegimes and needs to make sure none of them go into business for themselves. Even worse, the zzaburi have their own power structure that he is only the guardian of, not the head.
One big revenue source that Guilmarn has exploited is that of trade from the Iron Hills and between the Quinpolic League and Safelster. That he can tax the heck out of and not share with his caporegimes.
Loskalm has a similar if opposite problem. Everything in Loskalm is part of Siglat’s perfect social order. The King of Loskalm is owed duty and service from his subordinates, and in return, owes them other duties and responsibilities. During the Ban this all worked perfectly, but since then imperfections constantly creep in. Worse yet, Sog City has become the main entrepot for trade (especially with the distant Lunar Empire).