I dont know much about prequel but out of curiousity what role do the Thalmor play in this?
They don't exist yet.
This is set just before (presumably) The Elder Scrolls 4: Oblivion.
At the end of the events of TES:Oblivion there is no Emperor of Cyrodiil and the continent is left quite weakened.
Furthermore the Summerset Isles suffered greatly by the Oblivion CrCIA and were unhappy with the support and protection provided by the Empire.
The Thalmor, a group of Mer Supremacists, were given power in Summerset Isle.
As a result the Aldmeri Dominion formed (consisting of Summserset Isle's Aldmer, plus the somewhat oppressed Valenwood Bosmer and the very oppressed Elsweyr Khajiit), which declared war against the Empire.
This took quite a while and both sides took great losses, but the Empire was slightly worse off.
The White Gold Concordat was signed, forging a treaty. The Thalmor would enforce the Concordat throughout Tamriel. That leads up right to the beginning of the events of The Elder Scrolls 5: Skyrim.
It's a little bit more complex than that though, but that's the basic premise behind the Thalmor and the Aldmeri Dominion of TES:Skyrim.
You can read more here;
http://elderscrolls.wikia.com/wiki/Third_Aldmeri_DominionIt does contain spoilers to TES:Oblivion and TES:Skyrim.
Loved the update.
Hoping the pace keeps to this or even picks up too.
