From SWTOR.com:

"Jedi Master Gnost-Dural has entered a new holorecord in the Jedi Archive. After a thorough analysis of the evidence, Master Gnost-Dural has discovered that the Mandalorians’ return to the galaxy and alliance with the Sith was no coincidence—it was the result of years of shadowy machinations by the sinister agents of Imperial Intelligence.

BTC 14 – Frustrated by a series of Republic military victories, the Empire began exploring alternative strategies in its drive to conquer the galaxy. Despite the tantalizing offers of Imperial Diplomats, members of the galaxy’s notorious underworld refused to swear allegiance to the Sith Empire. Thus, Imperial Intelligence began laying the groundwork to win the underworld’s loyalty through other means. Infiltrating the gladiatorial arenas of Geonosis, Imperial agents fixed the fights to cultivate the rise of a new Mandalore—an Imperial puppet who would call forth some of the galaxy’s most proud and independent warriors to unknowingly aid in the Empire’s dark designs.

Watch the fourth Timeline holorecord, The Empire Changes Strategy, narrated by actor Lance Henriksen."