Sort of.

The Sith culture had existed in a primitive form for millenia prior to the arrival of the Dark Jedi, spurned by the Jedi Order in the results of the Great Schism. The true Sith - also known as the Massassi - died out finally in the Exar Kun war, though their decline had been coming since the days of the Great Hyperspace War (the original conflict in which Naga Sadow and his minions attacked the Republic).

The Dark Lord title was first taken by Naga Sadow and his followers, including Marka Ragnos. The title did not exist in primitive Sith/Massassi culture, and "Darth" was taken (excepting the non-canon origin in KotOR) only by Darth Bane after the great conflict on Ruusan and the death of Lord Hoth and the Army of the Light.

Good general idea, though, even if it is 4000 years off in time perspective...