My Dad’s family is of Irish descent and have the same dark features you describe. When I researched the family name I discovered they descended from the “black irish” which resulted from the spanish invasion of Ireland. That might explain your family’s dark features as well. Worth researching, if you’re curious.
I have heard several “Black Irish” Theories with the Spanish Sailor theory being the most common. Google “Black Irish” and you can see that there are many different explanations, but none have been proven. And some claim there is no proof the Spanish sailors breed with enough Irish to have the affect they claim it did. In any case I don’t know if my clan was in Ireland long enough to intermix with Spanish/Irish. We were Scots-Irish as were many of the people in Northern Ireland (Ulster). My family moved from Scotland to Ireland in the 1500’s and then to America about 1750. Most Scots-Irish did not even interbreed with the pure Irish on the island, keeping the bloodline pure Scot for generations. So even though my GGGG Grandfather was born in Londonderry and his family live in Ireland for about 200 years they were probably pure Scot.
The first known invasion (record in history) was about 700 BC. That's when the three brothers (sons of Ir) sailed their ships to a new land they called Scota.
Through time Scota became known as Irland (after Ir) and Alba became Scotia or Scotland.
The earlier population had all the black hair. The new invaders from Ireland had the red hair. The titled nobles had originally come from the Volga. They took over the Westernmost Basque region. Undoubtedly they took a lot of Basque slaves with them because today's Irish population cannot be differentiated from the Basque people on the Continent.