Forum:KB:Why is Darth Plagueis listed as having died "Prior to the Battle of Kashyyyk"?

If you look on plagueis' page then you'll read that he died prior to the battle of kashyyyk, basically before the events of Episode III: Revenge of the Sith for those of you who don't know what that battle was.

I'm assuming it's because that's the earliest mention of him that exists in the new canon, but we know from Episode I: The Phantom Menace and Star Wars: The Clone Wars TV Show that Darth Maul was referred to as "Darth" before his fight on naboo with Qui-gonn jinn and Obi-wan kenobi, which would imply plagueis' death taking place before the invasion of naboo, perhaps further.

For now I'll be using the Legends date of his death, 32BBY, but if anyone can tell me why then please do.