Treaties were really between people rather than realms up until the idea of 'country' took hold in the early Renaissance. You see some of the same things in BM when rulers change and the new ruler doesn't care about previous agreements. Some people go 'well yeah duh why should the ruler care' while others insist that the treaty was on behalf of the realm (which it was) but so much of medieval politics was personal that both sides are right. FEI is a perfect example of this. 'Relations' between Zonasa and their neighbors haven't changed all that much: it's not like some huge group in Zonasa always hated Kindara and Cathay just as there's certainly no group in Cathay that hates Zonasa any more than there ever was. But you change the guy in charge and all of a sudden you have a completely opposite picture of what you had days before that.
Or imagine what would happen if Morgan or Jenred unpaused right now. Entropy. It would be glorious. Not necessarily beneficial to any of my characters, but glorious all the same.
One other element you did have in medieval politics that we don't really have in BM is the role of the Pope. If you really wanted justification for your war, you got the Pope behind it (as William the Conquerer did when he invaded England). Or if you were losing, you got the Pope in your corner to sue for peace. Pissing on a treaty with the Papal seal was a lot harder, at least depending on which Pope you had in office at the time. BM religion is still in its awkward adolescent stage as BM doesn't have the population to support both a First and Second Estate even when it does have big religions like SA - it has to marry the two and it's pretty tough to be a priest in a realm with multiple religions where the ruler ain't on your side.
