Alright, I just started again after not having played for a while. But I recall reading things occuring in one of the patches which ends with the Horde getting kicked out of Dalaran. Now, I've completed the intro events for the Krasarang Wilds 5.1 quests and the Isle of Thunder quests, as well as having done the Lorewalker Cho scenario quests. But I haven't found anything related to the Dalaran stuff yet. Where can I find this?
It's part of the 5.1 reputation storyline. As you gain rep with your faction's…faction, new quests will appear that tell the story. So if you want to experience that, just keep working

I didn't find the right solution from the Internet.

References:
http://www.mmo-champion.com/threads/1337383-Lor-Themar-Sunreavers-and-Dalaran

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