Warrior Lore (Is it a thing?)

[Enkidoh]

One might imagine that Sea Wolves came from the north and some opted to stay in the volcanic Farreach, later adapting to become Hellsguard the same way the Lalafell adapted from the plains of the south seas to the dunes of Thanalan.

I just want to add one thing to your excellent description Moose, but it was officially confirmed a long time ago that the Sea Wolves did in fact originate in the north of Hydaelyn. The main FFXIV site has stated this clearly since before ARR's launch:

Roegadyn

The Roegadyn are easily identified by their massive, muscular frames. They are descended from a maritime people that roamed the northern seas, though many of their ancestors turned their longships south to brave the crossing into Eorzean waters.

This also explains why the flag of Limsa Lominsa features a Viking-style longboat instead of a more 'modern' looking vessel - it's the style of boat the Sea Wolf ancestors of those who founded Limsa first used to arrive in Eorzea. But I digress...