"Scotland and Ireland were occupied separate countries with individual cultures"

Really Jom?

Scotland most certainly was an independent country united under one ruler, one church and one legal system. Please tell us all when before the arrival of the Normans the same could ever have been said of Ireland.

As to "occupied" - what work of alternative history did you pluck that from?

IIRC Scotland and England were two separate countries in 1603 when on the death of Queen Elizabeth the First the reigning Scottish King ascended to the Throne of England - no invasion, no battles, no occupation. The two countries remained separate entities until 1707 when the two Parliaments united - no invasion, no battles, no occupation - Scotland still retained her own church and her own legal system.

Also IIRC the Normans were "invited" over to Ireland by one disgruntled Irish "King" who was in dispute with a couple of other Irish "Kings" and required outside help to hang onto his "kingdom". Unfortunately for the disgruntled one the Normans on arrival did what they did best from Ireland all the way east to Aleppo - they held onto any land they fought for, then assimilated with the local population.