While that would be a specific instance of it, my understanding is that "the pale" would refer more generally to the fence, or palisade, that encircled a town (made up of wooden stakes, or "pales"; this is also the origin of "to impale"), and "beyond the pale" simply meant "outside the protection of the town", and thus, metaphorically, outside of what's right and proper.

....In fact, Wiktionary states [0] "According to the Oxford English Dictionary, there is insufficient evidence that the term originally referred to the English Pale, the part of Ireland directly under the control of the English government in the Late Middle Ages".

[0] https://en.wiktionary.org/wiki/beyond_the_pale