Legends of Dune
As explained in Brian Herbert and Kevin J. Anderson's Dune: The Machine Crusade (2003), the family of the Titan Xerxes had originally ruled Ix. When Tlaloc had conquered the Old Empire, Xerxes had taken control and changed the name of the planet from Rodale IX to just Ix. After the fall of the Titans at the hands of the thinking machines, Ix had become one of the Synchronized Worlds. In the novel, Ix is finally liberated by the Army of the Jihad in 175 B.G.
Read more about this topic: Ix (Dune)