[@Pyromaniacwolf]Yep.  In the last war, in stead of Darth Bane killing the Sith off, he and most of the properly trained Sith were killed in battle against the Jedi and the Republic.  The last surviving true Sith Lord took the throne, but a Jedi strike team managed to fight their way into his palace on Korriban and kill him.  The surviving Sith were forced to surrender, but instead of absorbing the Empire the Republic allowed to maintain all of its uncontested systems in exchange for surrendering and signing a 100 year peace treaty.  Those with Sith racial blood haven't been seen since, and most people believe they died out during the war.