How to Hunt for the Ring as Mordor?
I've started my first Dawnless Days campaign recently. I was playing Mordor and doing alright against Gondor. But I don't really understand the hunt for the ring mechanics. The first mission I got was asking me to pillage, loot, or raze a ton of settlements hoping that the ring was there, but there's no way of realistically getting an army up there without abandoning crucial areas like arnor.
So I'm wondering how the mechanic actually works. Do I, as Mordor, have to personally pillage my way through basically all of the north, or does it also work if Isengard, Dol Guldur, etc. take those settlements? Having to do it all by myself feels like a rather weird mechanic.
Hopefully someone can explain how it is actually supposed to work.