The Atoan system was a star system that was located in the Ghost Nebula, in the Expansion Region. It contained Atoa, the Atoan homeworld, and some other settled worlds.
A major campaign for the Imperials took place in the system shortly after the creation of the Galactic Empire. Darth Vader and the 501st Legion were sent to investigate the disappearance of Admiral Garoche Tarkin. In actuality, he had defected to Lady Saro, High Priestess of Atoa, one of the rulers of the system. Saro and Tarkin were eventually killed by Vader.