It should be noted that there are a few errors in Master Baas' accounts of the Jedi Civil War.
Revan and Malak were annointed Dark Lords of the Sith by a mysterious Sith Emperor, who lurked in the Unknown sectors of space. This Sith Emperor corrupted the former Jedi champions and dispatched them to locate the Star Forge, a super-factory that the Emperor would use to hasten the production of his armada.
The new Sith Lords located the ancient Star Maps and followed them to the Star Forge. They used the Star Forge to build a powerful invasion fleet. They were also joined by those who served during the Mandalore Wars. The corruption of the teachings of Malachor V turned many Jedi to the Dark Side, and veterans of the war quickly joined the two Sith Lords.
*Revan used a unique power to learn the Rakatan language, what was that power?
These are not "errors" it's called Plot Holes and NOW the Old Republic area is full of them. First of all: Revan and Malak are supposed to be THE dark lords of the sith, it was first ruined after the KotOR2 but it was not so bad since they don't tell it why he left (you could think anything for example some kind of Yuuzhan Vong threat)the writers simply didn't want the Player to play as Revan again and they had to take him out of the picture somehow. The second and the worst was this "Empreror" thing - before I continue let me clear something. The title "Darth" was found by the Rakata and (maybe) they gave it to Revan after he traveled to Lehon. NO ONE used it before them, not even Vitiate (He was called Lord Vitiate by Marka Ragnos) since he didn't find any Rakata. !?AN OTHER PLOT HOLE: How come the Emperror does not use the Darth title but every other sith lord does, it's like LORD Vitate gave this title to Revan and every other sith who he seems to deserve it?! I hope you can see what I want to say here. - this Emperror was created for an MMO (a pourly written MMO) where he is the "Aizen" (from Bleach if someone doesn't know it). Now for the next Plot Hole: Revan and Malak started to fall to the dark side in the Mandalorian Wars and find the first star map on Dantooine. Not because of an Emperor, since they met with him AFTER the Mandalorian Wars http://www.youtube.com/watch?v=bgH7Pb4GN_Y
as you can see here, it's not like they were possesed by someone. I really don't want to speak about this anymore it's F**ks up my mind...really. NOW to the another plot hole: Before the KotOR Revan had to use the force to learn the Rakatan language AND put the republic basic in the Rakatas' head so they can understand each other. In the SW:TOR every body (even the stupidest Smugler) can understand every Rakata (and Esh-kha) and their ancient language and these Rakatas and Esh-khas can understand the republic basic. So again how come this happens? I hope you can see now that Master Baas is not wrong, more like these game writers are (because they are f***in morrons). If Revan would have left the known space because a Yuuzhan Vong (or any other kind of) threat, it would make more sense and they wouldn't have made this much Plot Hole in the Sith Order or in the game.
Edit: I writen this before I readed any comment here, but now I see there are problems (darth) that lot of other people realized.