The Myth of the Sith

There is this debate happening in the Star Wars fandom about whether The Acolyte has broken canon due to the Stranger (I do not want to spoil his identity for anyone waiting to watch it) revealing himself to be a Sith. I am not going to get into the debates about the show, and the insanity of the fandom, but instead want to focus on this portion of the debate. 

Basically, fans claim the Jedi said in episode one that the Sith had been extinct for a thousand years. So if that is the case, a Jedi could not have fought against the Stranger in the show. However, we know the Jedi are wrong in this case because Darth Sideous and Darth Maul are operating during this time. Clearly the Sith are not extinct. 

Here is the exact line from the movie:
Ki-Adi-Mundi: Impossible! The Sith have been extinct for a millennium.

The Jedi Council is clearly wrong about the Sith. And, if the Sith did encounter Jedi from the time of Darth Bane to Darth Maul, that probably means the Jedi did not survive to inform the council. OR if they did survive, that means they probably defeated the Stranger and assumed he was the last one. Hear me out, okay, there will be spoilers now. 

If Master Sol catches up to Qimir and Osha, and he hears about the rule of two, then when he defeats Qimir, he will assume that Qimir was the master, since he was trying to train Osha to be his apprentice. Master Sol returns to the Jedi Council and informs them of this “Sith.” They dismiss it as just a Dark Jedi who was trying to resurrect the Sith of the past. 

This would explain how Master Yoda knew of the Rule of Two at the end of episode one. Now look, if you think the Jedi Council is not capable of keeping things out of the official archives, then you have not been reading the High Republic books. In phase two, Yoda decides to keep the knowledge of the Nameless out of the official record because he does not want the enemies of the Jedi to seek out such a powerful weapon against them. It does not work out well for them 150 years later. It is not crazy to think the council would ignore this information about the Sith.