Beyond the pale...

...bu what is the pale?  Well a pale is a pointed stick, or stake (from the Latin palus) and from time immemorial societies have delineated their boundaries with fences, which are just pointed sticks stuck in the ground and linked together.  So long as you were inside the fence you came under the protection of the tribe, but once you ventured "beyond the pale" you were on your own.  Over time, the expression has come to mean going beyond the bounds of acceptable behaviour.