Itís a bit late for TOG but hereís an idea I just had regarding tribal wars.
When you declare a war you target the whole pagan part of a duchy, regardless of which tribe owns it. That means you start a war with every single pagan landholder who controls at least one barony in the target duchy. There is no truce after the war but you can only target the same duchy once every 5 years. There is no warscore, instead there is a timer. When the war starts you have 1 year before it will end. Every successful siege increases that time by a month. Every lost battle decreases it by a month. Once the timer runs out you get every pagan holding you occupy in the target duchy.
Itís just a rough draft at the moment, but what do you think?