Forum:SH Archive/Jedi Apprentice Series

I've just got a question regarding the Jedi Apprentice series, when Qui-Gon is training Obi-Wan. There's a book. I don't remember the title, but It's got Qui-Gon facing off with a Sith on the front cover.

How can this be possible when Qui-Gon and Yoda revealed that the Sith have been "extinct" since the reign of Darth Bane? I mean, in Episode I, Qui-Gon didn't even know what Darth Maul was. Don't you think he'd remember what a Sith was like if he'd met one before, supposedly?