Well, yes, but technically the archipelago is cut from the rest of the world as sail is a rarity at the moment, so I am unsure if Yorum had an effect on it. 

But whatever, the history of the region is unclear as heck. I am of the opinion that humans flooded all corners of the sea, most being killed or enslaved by established Hain, but that is just a proposal, we could just assume it was a third or more Hain or something. Having some Hain lore about the flooding would be neat though. Wink. (Though maybe they had higher mortality rate so Hain refugee were rarer)