According to that wiki link the first ones to discover the 'greater power', turn Dark Jedi were exiled and they fled to Korriban and became rulers of the Sith.
The Dark Jedi who conquered Korriban and the Sith race were not the first Dark Jedi. The first Dark Jedi were the Legions of Lettow. The conflict between the Legions and the Old Jedi Order was known as the First Great Schism and occurred around 24,500 BBY.
The Dark Jedi who fled Republic space in exile, who discovered and conquered Korriban, declared themselves the Dark Lords of the Sith, and went on to found the first Sith Empire fought in the Hundred-Year Darkness (or Second Great Schism). This conflict occurred between 7003 - 6900 BBY.