Heh, I think we may end up _buried_ in drums.
If you can spare a stack of soldiers, it might be
useful to attack anything that moves into the province,
or maybe just Independent Player [100]. There's a
short interval between arrival and beating the drum to
summon the next group of savages, so killing them during
this time might break the cycle. I haven't had a chance
to try this yet, personally, so I don't know if it'll work.