I’m working on a project and I need ideas for points of conflict, cooperation and assorted bits of intrigue between small independent states during the Middle Ages. This seems like something that would have a data base somewhere for RPG games but I come up with bumpkis. Perhaps your Google-fu is better than mine (it just has to be) or you have other ideas than what I’ve come up with so far:
War
Genealogical claim
Spies
Trade agreement
Brigandage
Mining concessions
Trade route taxation
Assassination
Marriage
Fromenting revolt
Bank loan
Peace treaty
Ecclesiastical investiture
Mercenaries
Guild or town charters
Fishing rights
Refugees
A good wiki-walk might produce some actual historical examples and incidents you could base your policy-germs on, especially if you expand the timeframe (i.e., taking events from the Imperial Roman period, or the late pre-industrial era), or look for relatively lesser-known examples from outside of Europe.
Anyways, you might try…slavery. The trade (establishing, cornering the market on, attempts at outlawing, etc), rebellions, technology making it obsolete or newly profitable, all sorts of good stuff.
Trade secrets. Many countries refused to allow some people to move to another country because these people knew some trade secret that the first country was trying to maintain as a monopoly. Say, for example, your metal industry could make a particular alloy. You would forbid any metalworker who knew the alloy’s formula from leaving the country. That way you could remain the only source for this alloy and charge higher prices.
And, of course, you were at the same time trying to entice people into your country who knew trade secrets in other countries.
Blood libel – one community/state wants to start a war with another, so its agents spread rumors that the other side is capturing their children for ritual sacrifice.
Peasant revolt.
Water rights – a river runs through two states, and one side dams it up which means it runs dry through the second state.
Loan default. A loans money to B, then B says go screw.
Locusts.
Gold/mineral strike, either in one country that changes the balance of power, or on the border so the two states can fight over it.
Succession crisis. The monarch dies. A says Y is the heir, B says X is the heir.
The old alliance cascade. A declares war on B. But C is allied to B and comes to B’s aid. But D is allied to A and comes in on A’s side. Then E, traditional enemies of D, join side CB against AD.
I’ve played so much Crusader Kings 2 that I can rattle these things off the top of my head. For example:
The king of a small border country is afraid that his brother, also king of a neighboring country, is out to get him. When the old king their father died, he divided the realm between his sons. Now each stands to inherit the other’s kingdom should he die before producing an heir. So the king wants to do unto his brother before his brother does unto him. Did I mention a third brother, also king of another country, who probably wants to do unto them? In the meantime there are hordes of infidels who want to take over all their kingdoms. Can the brothers can stop fighting long enough to present a united front?