Umbaran / Legends Umbarans , culturally known as the Shadow People , resided on the dark world of Umbara deep within the Ghost Nebula . Umbarans could see in ultraviolet ( below 300 nanometers ) and had the ability to read , subtly influence , and sometimes control the will of others . Biology and appearance . Umbarans spoke the language Umbarese which was written using the Umbaran alphabet . Umbarans were gaunt , frighteningly pale near - Human s with achromatic sunken eyes . Due to the Umbara ' s eternal twilight , their eyes were well adjusted to the dark , but they were easily disoriented when exposed to bright sudden flashes of light . The Umbaran militia , who took part in the battle of Umbara , wore air - tight helmets that fed them a potent mixture of gases , which enabled Umbarans to be more effective in combat . Umbarans were highly isolated and manipulative . A societal caste system promoted cultural goals of power and influence . Many had a darker sense of humor than the average Human , which would manifest in social interactions . Masters of misdirection , these creatures almost never revealed their true thoughts or intentions . Society and culture . Umbaran society was built on a finely detailed caste system comprising almost one hundred levels . Only those in the top ten caste levels were given the opportunity to leave their homeworld , explaining their rarity outside the Ghost Nebula . The primary ambition of the average Umbaran was to ascend through the caste levels , using tactics from blackmail and subterfuge to cool assassination , thus priming them for a life in politics . Failed plots to ascend the ranks of society were met harshly with the attempted perpetrator imprisoned and their family dropped to one of the lower caste levels . Dependent upon the rank of the targeted individual , the perpetrator risked a death sentence for themselves and their entire family . Successful maneuvering however , was rewarded with prestige , making it worth the risk . They could also tell if a person was lying due to their more sensitive eyes and their ability to sense heat . The highest caste level , known as Rootai , comprised a council that ruled Umbara , and its members were considered royalty . The Umbarans also had their own military known as the Umbaran militia who protected Umbara and the Umbarans from invasions . History . Umbarans had a presence in galactic affairs since the dawn of the Galactic Republic . Although few in number , they were always at the forefront of politics . During the time of the Galactic Republic , they strode eerily through the halls of power . Respected , yet feared for their ability to subtly sway others , Umbaran senators rarely met anyone foolish enough to call them an enemy . It was a fallen Umbaran Jedi Master by the name of Phanius that touched off the first in a series of conflicts that eventually came to be known as the New Sith Wars . Nearly a millennium later , the Umbarans allied with the Brotherhood of Darkness against the Republic . An academy to train Sith assassin s was opened on Umbara . Umbaran shadow spies served the Sith on planets such as Ruusan . During the waning years of the Old Republic , Umbarans used their natural mental sway to secure positions of power . Supreme Chancellor Palpatine selected an Umbaran by the name of Sly Moore to be his Staff Aide . Moore was entrusted with some of the soon - to - be Emperor ' s darker secrets . During the Clone Wars , the Umbarans seceded to the Confederacy of Independent Systems following the murder of Umbaran Senator Mee Deechi . During the Jedi Purge , Umbarans were used as spies and thought police , with a main objective of weeding out rogue Jedi who escaped the onslaught . During the Galactic Civil War , Umbarans would help the Emperor find Rebel sympathizers hiding within the ranks of the Imperial government and military . The death of the Emperor at the Battle of Endor caught many Umbarans by surprise . Fearing retribution from both the Imperial Remnant and the New Republic , the Umbarans fled civilized space back to the Ghost Nebula . Umbarans often wore Shadowcloaks .