Demonic Kings or how you want to call it. These seem to rule over some legions, I know though that this rulling system is more complicated than it sounds, although I don't know more than that. Do you think that these Kings have soceities actually, in the other rounds?
When looking up information about the demon kings it is a good idea to read of them within the context of their presentation. It seems like the bulk of the information is related to biblical mythos involving the demon kings, princes, and legions. In what I have found their hierarchy is treated as a mirror to that of the archangels, seraphim, and the rest of the heavenly host. So I imagine any ideas of society or function would likely also be comparable. Though naturally also the opposing side of the light-vs-dark Christian equation.
I did some sleuthing and actually found a blog post that pulls together a lot of information very well. I'm not familiar with the writer but he/she did a lot of work on the topic and it is quite thorough;
Heres is one I had found years ago while trying to base my dnd lore off of but turned into actual research
There are huge complicated webs of societies and factions in the higher dimensions for these beings, as their numbers outweigh ours on just one sphere in space, while they can populate many spaces and stretches on the plane, and whos to say that their dimension even includes planets and even comparable laws of physics that we have here? Since their world operates on very different grounds, so does their societies. If you befriend one, Im sure they will tell.