I suspect the drow memory shard stuff predates the 120 years ago mark, but I can't be sure. It's a shame they don't let us ask Dhourn what year he's from.
Regardless, I'm not convinced that the time of Dhourn, Xargrim, and Filro are all that important to the big narrative. These are minor figures who sought to rediscover the Grymforge, and probably failed to do so some time before the Sharrans took the area over.
Just my guess right now though, based on the little we have to work with.
