Board Thread:Lore Discussion/@comment-81.103.152.214-20140212201133/@comment-1600847-20160614120914

The Thalmor probably hate the Dunmer. For one, Morrowind is a province of the Empire. Second, the Dunmer are Daedra worshippers. Third, the Dunmer's Chimer ancestors left the SUmmerset Isles after a feud with the ancient Altmer, so if the Altmer hold grudges (which wouldn't surprise me) they're likely still bitter over that feud.