Umbara

Umbara, the Shadow World, never sees its own sun: perpetual twilight lies over bioluminescent jungles where everything - flora and fauna alike - glows, lures and kills. Its isolationist Umbarans field advanced technology decades ahead of galactic standard, from ray-shielded tanks to starfighters controlled by thought.

The Republic's Umbara campaign is remembered for its commander: Jedi General Pong Krell, whose deliberate sabotage - sending the 501st against disguised friendly forces - forced Captain Rex and his brothers to arrest and execute a Jedi. The campaign planted the seeds of Rex's later doubts about command... and prepared him for Order 66.