"The rest of the Second Era was a time of great darkness and chaos throughout Tamriel, nowhere moreso than in Cyrodiil. Without a central government, Nibenay and Colovia split apart, farms fell fallow, villages were left in ruin, and the former Imperial highways became no man's land, the realm of bandit kings. The Imperial City itself became the prize for an endless series of would-be emperors, fought over for centuries until its glory was only a faded shadow of the great days when it ruled Tamriel."
So, clearly the Alliance war and the fights for the throne etcetera do fit in with the lore. The only thing really added into lore is Molag Bal trying to pull Nirn into Coldharbour.
I had completely forgotten about this book until last night when I randomly found the copy a friend gave me!