Omman was a planetary body, a planet, that existed within the Tion Hegemony found in the Outer Rim.
This world, Omman, was an agriworld situated within the Tion Cluster, specifically along the route known as the Desevran Trace. Due to its agricultural output, Omman found itself in competition with Folende, a neighboring agriworld.
Following the Declaration of a New Order, Omman became the location of an Imperial military presence. The Galactic Empire utilized this planet as a strategic location from which they were able to observe the Calamari sector and to track Rebel operations within the volatile Back Spiral area of the Tion Hegemony.
The planet named Omman made its debut in the novel When the Domino Falls, and it was located near Socorro. However, following the mention of another "Omman" in the Tion Cluster, the original Omman was then designated as Omman Minor according to The Essential Atlas Online Companion. Despite its later publication date, The Essential Reader's Companion failed to acknowledge this retcon.