I forgot entirely about the Great Sundering and the Night Elves treatment of the Tauren at that point of time.

Guess it still gives them a little more ground.

I'm assuming that Malfurion's book will have at the least a tiny bit of info of the happenings between killing Achrimonde and the start of WoW, maybe that's where Blizzard will finally decide to make the connection. Perhaps the Night Elves asked the Warsong clan to stop, and they didn't, which is why Warsong Gulch is so heavily contested, maybe the Alliance promised to help them defend Warsong in exchange for them joining the Alliance, or something deeper. Though I think it's probably a combination of Warsong refusing to stop cutting down the forest, and the Alliance's willingness to help them defend it.

Though I'm starting to wonder where the Horde is going to get thier lumber at beyond Cataclysm. It seems Ashenvale is empty, so they'll have to start moving on to some other place. Maybe Stonetalon will have grown back during the cataclysm, or even better the new Desolace is full of trees that reproduce quickly due to highly enriched soil. Or something like that.