Umbara is a planet in the Expansion Regions, featured in Star Wars: The Clone Wars. It is the planet where Rex and his fellow clones fought under Pong Krell and learned he was a fallen Jedi.
After the fall of the Republic, the planet was under the oppression of the Galactic Empire. During the Imperial Era, an uprising by Nightswan, Thrawn's arch-enemy at the time, was engineered but stopped by Thrawn.