Tuat is a planet on the Kaliam galaxy which is location for the Tuat Goa'uld base.
The planet has been ruled by Ra for a long time. His lieutenants even established the planet as their neutral ground for their high council. It was visited by Hathor upon Ra's death.
The planet is known for suffering a natural phenomenon similar to earthquakes called a Tuat-quake.(Stargate: Rebellion 2)