Free Jaffa formerly in the service of Heru'ur. After the fall of the Goa'uld Tass'an and many families settled on Sartorus to enjoy their freedom. Eventually a Prior of the Ori visited the planet and instructed that the people worship the beings.
When Tass'an and the others chose to resist he witnessed the Prior's subsequent return. He dialed the chappa'ai and planted his staff into the ground. In moments Tass'an's city and hundreds of his Jaffa were destroyed.
At the request of Teal'c and Daniel Jackson Tass'an later came to Stargate Command to tell the story of Sartorus and its fate to the Sodan Volnek, who believed the Priors to be benevolent. Volnek would later return to P9G-844 with this story.
Babylon - Tass'an visits Earth and tells Volnek what a Prior managed to do to his people and city on Sartorus.