Umbara is a planet that was aligned with the Confederacy of Independent Systems during the Clone Wars, with Clone Captain Rex serving there for a time. Some years afterwards the planet was the site of a battle between the Imperial Navy and a force of Vulture droids controlled by a mysterious criminal named Nightswan. Then Lieutenant Thrawn was of the opinion that the clash was orchestrated as a means of allowing the Galactic Empire to seize control of Umbara's mining facilities, making it easier for smugglers to obtain the valuable mineral Doonium.