Comment by jimmygrapes

Off the top of my head: common law (sometimes codified), Catholic/Christian morality (as an accepted ideal) and ritual (less important but still cultural glue), lessons learned from the French Revolution, and some significant "my old enemy is my friend vs these new strangers" mentality born over hundreds/thousands of years of war with each other while natural geographic barriers mostly reduced interaction in the populace with those of particularly different looks (aka "racism" except far more nuanced).