@dnkboston @Tarnport
Trade was geographically limited, probably (I'm not so good at history), but I can remember banks were invented in the middle age the same for checks and bills of exchange.
In the middle age the rule of law wasn't arbitrary it was just unbalanced, on the side of nobilty privileges. However, rules were written and there were courts where you could ask for your rights to be respected (if you were so high in the hierarchy to have rights).
Is this a step back with regards to what there was before the "dark age"? Well... roman empire had slavery, if a slave killed his master the family had the right to kill ALL his slaves (men, women and children). At the end of Spartacus's revolt 6000 prisoner's were crucified on the road between Capua (the city were the revolt begun) and Rome.
Saying that civilization went down in the middle age (that's the reason behind being considered a dark age) is risky...