Ishkur
From The Stargate Omnipedia
A Goa'uld who ruled five millennia ago. Many of his Jaffa would later flee from the Goa'uld domain and become the Sodan. As they advanced through the ranks and became more involved in his service they realized that he was not a god, but an impostor.
When Ishkur branded them traitors and ordered their deaths the Jaffa tried to fight against him, but were outnumbered. A group of them set off into the galaxy to find the legendary sanctuary world Kheb, and later settled on P9G-844 -- calling themselves the Sodan.
KEY EPISODE
Babylon - Lord Haikon tells Colonel Mitchell of the origins of the Sodan and how they served under the Goa'uld Ishkur.