http://www.oxm.co.uk/49108/features/skyrim-dlc-redguard-predictions-dragonstar-hammerfell-and-the-isle-of-stros-mkai/
"There's also the conspicuous absence of the border city of Dragonstar from Skyrim as it stands. According to the Elder Scrolls wiki, the city is (or at least, was) a hotbed of political contention, chopped up Berlin-Wall-style between the Nords and Redguards in the aftermath of a long-ceased war."
When I see this, all I can think is; so this is how the Thalmor plan to cause/widen the rift between Hammerfell and Skyrim.