The Lost Faction

As the Erudite Initiation draws to a close, Erudite Initiates Sundeep Nayak (Erudite-born), Caleb Prior (Abnegation Transfer), and Xella Goodall (Candor Transfer) are tasked with presenting their knowledge of History. As the trio divides their subject into thirds, Xella Goodall is tasked with researching the history of the 5 Factions; but were there only 5?