"So, uh, basically, it's all about ritual - targeting? Uh. I am not equipped to give a lecture on ritual theory. Domicia?" Aelea looks hopefully at one of the staff-wielders.
"Okay, basic ritual targeting. You can target a ritual in - lots of different ways, but two of the most common are - presence, and dominion. If I'm right there in a region, I can cast a region-affecting ritual on that region. If there were any, any more. If I'm in a territory, I can cast a territory-affecting ritual on that territory. If we had nation-affecting rituals that'd work the same way - although actually I think you target those through the egregore - except that might be on the people, not the place - it's complicated, sorry. Oh, and we can cast Empire-affecting rituals on the Empire in the same way, I think - although maybe you have to be in the Imperial Regio for that? I'll get to that later.
You can also cast by dominion. If you want to cast a ritual on a territory, but you're not in that territory, you can cast it on the Senator for the territory, if you've got one - that's targeting by Dominion, rather than Presence.
But you can only have an effective Senator for the territory if the Empire controls enough of the regions in that territory - control enough regions, and we have magical Dominion over the territory as an Empire, and then can delegate that to a Senator, and then people can cast through them.
And then there's the Imperial Regio, which is a specific special place in Casinea, in Anvil - from there you can cast on any territory that the Empire has Dominion over, whether you have the Senator there or not. Or region, I guess, if you had something that targeted a region. But nobody does that any more because it's no more expensive to target the whole territory.
That... probably wasn't a great explanation, sorry. Not only am I not a teacher, I'm barely even a ritualist, I'm mostly a battlemage," Domicia apologises.