The Mandalorian Wars serve as a prequel to this event, in which Jedi Knight Revan and his then apprentice Malak disobey the Jedi Council to take part in the war.
Not only did this reveal that there even was a war between the Jedi and the Mandalorians, but it could be a reference to the Mandalorian Wars, a big set piece from the Knights of the Old Republic video games.
It’s a big epic story with a series of comics and novels dedicated to it and technically none of it happened.
The games, which take place thousands of years before the trilogies, tell the story of the ancient battle between the Jedi and the Sith, in which the Jedi and the Republic were almost wiped out by a Sith Lord named Darth Malak and his ARMY of Sith warriors.