"Its just a Nord word for 'raiders.' We're told the reavers are out-islanders -- Nord raiders from the far north."

In Morrowind's Bloodmoon expansion pack, we see the groups of Reavers on the island of Solstheim. Presumably, I always thought of them as being Nordic pirates, like the historical vikings, and I interpreted the NPC quotes, as shown above, to mean that the Reavers were not from Solstheim, and that they also are implied to not even come from Skyrim, being from "the far north." Could that mean the Reavers were surviving Atmoran Nords that took to piracy upon Solstheim? If not the continent Atmora, where else could they come from that would be north of Solstheim?

There could quite possibly be islands all about the Sea of Ghosts which we don't know about, and that the Empire simply chose not to subjugate, either due to a lack of valuable resources, or because they were simply too remote to bother with. Solstheim itself is so remote that the Empire only built a fort on it because of all the pirates making camp there, and it only became relevant to the rest of the Empire when the ebony deposits were discovered. If it wasn't for that, everyone on the mainland would have been content with leaving it to the Rieklings and the Skaal. So it is not impossible that there might be other such islands.