I just thought that Horde nations are quite slow to expand, and there are quite rare cases of them blobbing disproportionally large. However, there were many examples in history where relatively small Hordes (land-wise) would suddenly gain huge masses of land, which I think in most cases was related to the sense of mutual goal between tribe leaders and presence of a strong chief. If united, nomadic tribes would normally cause varyingly big havoc: Turks, Mongols, Timurids, you name it.
So the idea is basically adding three levels of Horde laws for unity (low, average, high), which may be quite fragile depending on whether your ruler meets some certain requirements. It should be a dynamic system, which works similarly to how levy efficiency works, but with the ability to click on the next law upon meeting the requirements composed of the average of tribal opinion of the ruler, number of tribal vassals, absence of some traits and realm peace. The law shift may only occur towards the worse part automatically, but some rare events may either grant you more unity or less of it, depending on traits and random chance.
When you have high Horde unity, you unlock Empire level subjugation and +10% bonuses to levies. When it's low, you have -25% to levy efficiency. Quite simple.
So the idea is basically adding three levels of Horde laws for unity (low, average, high), which may be quite fragile depending on whether your ruler meets some certain requirements. It should be a dynamic system, which works similarly to how levy efficiency works, but with the ability to click on the next law upon meeting the requirements composed of the average of tribal opinion of the ruler, number of tribal vassals, absence of some traits and realm peace. The law shift may only occur towards the worse part automatically, but some rare events may either grant you more unity or less of it, depending on traits and random chance.
When you have high Horde unity, you unlock Empire level subjugation and +10% bonuses to levies. When it's low, you have -25% to levy efficiency. Quite simple.