i have circled and labled the locations of the differend vampire clans on this map Link (if the image shows up too small you should be able to zoom in)
hey, me and a friend decoded the oblivion text on the map, in case you cant read:
under solsthiem: An Imperial Province
under Vvardenfell: Morrowind Province
under Mournhold: (there's a typo) capitol cit(y) of "Morrowind"