Народно Събрание, or just Събрание.
Sabor is a village gsthering the type you do on the patron saint'd feast day or for other such occasion.
Skupshria, that is Serb for the same type of parliamentary assembly.
Stopping serfdom in Poland, which was quite rampant in Europe, might be a bit hard.
Is that King John II Casimir ?
I thought he was mostly sabotaged in his reforms and did moderately well, given the circumstances?