The Sith had existed and had been the powerful user of Dark side... But they were a culture that could not survive.They killed themselves off long ago.

Obi-Wan had heard stories about the Sith. But it was existence uncertain for him.

Those who were the Jedi once were also in the Sith.

And they attacked the once friends.

Is Dark side stronger than friendship, love, and Force? He didn't understand.

TBC