perhaps the Soul Cairn we visit is somehow related to Skyrim's souls since that's where the portal to is bound from.
I considered this, but it doesn't explain the presence of a certain Dunmer soul from Morrowind you meet there.
Yeah, I theorized for myself that it was just the "nordic" part of the Soulcairn, because the portal was in Skyrim.
What bothers me more than the appereance of the guys is there equipment. They look different to Draugr actually, but they are wielding ancient Nord stuff.
Strange... maybe it is a heavily nordic influenced region of the Soul Cairn, but not exclusive for trapped Nord souls.
The dragon war actually happened before the eradication of the snow elves. When men were still in Skyrim, and not in Atmora.
The Dragon Cult arose on Atmora, though.
I don't think that your statement is correct, but the timeline of the ancient Nords doesn't make sense to me, so I may be wrong.