Originally Posted by
warnly
Post Third War Krasus, Rhonin and Broxigar travelling back in time, courtesy of Nozdormu, to before the first invasion of the Burning Legion, where they meet Illidan, Malfurion, Tyrande, Cenarius, where Krasus meets his younger self, Korialstrasz, Rhonin becomes Illidan's mentor, etc. and all that leading to the alteration of the timeline to what World of Warcraft essentially is.
Edit: We are talking World of Warcraft. I believe Warcraft 3 is set in the prime timeline, not the altered one.