History backwards
Gaelic spread to what is now Scotland from Ireland, while we were still invading our neighbours. That was of course before the Fitzgeralds arrived here on the latest step of their invasive path from Scandinavia via France and Britain.
Once here they quickly became assimilated in Gaelic culture, so that their king had to write an edict — in French — to attempt to stem their use of Irish language, customs and apparel. Furthermore, I speak Irish on a daily basis, do not live in the West, and am not paid to do so.