Also from the article: a “pale” is a fence. “Beyond the pale” used to require a suffix (e.g., “beyond the pale of reason”) but eventually by itself started to be short for “beyond the pale of acceptable behavior”.
Metaphorical boundaries of things like reason and acceptable behavior. “Beyond the pale” means outside the fence. Being “beyond the Pale of Settlement” (that is, outside the ghetto) would be a good thing.