Why might ruling a huge empire be more difficult than ruling a smaller one?

I think you want me to talk about empires for like history so here it goes.

If you have a huge empire it is hard to keep as it is further away, it costs more money, is harder to run and keep organised and people further away are different to you than someone close so will probably not want to be ruled by you.

Like if you are trying to take the place over you will have to send in your army and this will be harder if the place is further away rather than being close to you (it might cost a lot of money transporting people and weapons for example). Also people may be different so they could be harder to conquer like they might know things that you don't so it could be harder to defeat them. If you are trying to conquer a new place you won't know a lot about it for example.

I hope I gave you the right sort of answer.