The Origins of the Chiss are almost completely unknown even to themselves. Scientists believe that they are descendants of a long forgotten human colony which found its way into the Unknown Regions. Some genetic research done has indeed shown them to be a subspecies, probably linked to one of the Human races earliest attempts at colonizing the galaxy. Sometime before 27,000 BBY, a colony of Humans found there way into the Unknown Regions of the galaxy and eventually settled on a planet known now as Csilla, a very cold and hostile world, which delved even further into an ice age in 5,000 BBY. Only by taking to subterranean life did the species survive at all. It was the act of moving to the sub levels of the planet that fostered the changes that would lead them to becoming what is known as the Chiss now, giving them bluish skin and red eyes, very different from the Humans that they descended from.

The Chiss are believed to have established a life on Csilla sometime before the millennia-long ice age, and possibly even before the foundation of the Republic, putting them on Csilla probably during the Rakatan Infinite Empire. When the time came and contact was made with the galactic populous again, the Chiss had extended their government across a vast area within the Unknown Regions, which would later be known as the Chiss Ascendancy, which encompassed possibly as many as several hundred thousand star systems. The Chiss had controlled that many systems for at least a thousand years by the time they had made themselves known, yet, even they had not fully explored their territory, and had colonized even less of it.

Though the Chiss were not widely known to the greater galaxy, examples of their technology were known to exist as far back as 3,951 BBY when samples of their unique weaponry were being sold on the planet Onderon.

Government

Csilla’s government is controlled by twenty-eight major colony worlds which are scattered throughout Chiss space, known as the Chiss Ascendancy. This Chiss expansion into the Unknown Regions is believe to be due to the need to feed the extremely large urban population of their homeworld, which had grown to levels that were unsustainable. Estimates have been said to be just short of five trillion Chiss within the Ascendancy. The Chiss Ascendancy is known to be extremely untrusting and secretive, most members of the species keep to themselves, and are very untrusting of any outsiders, sometimes of other Chiss Houses as well.

Much of the Power in the Ascendancy rests with the Ruling Houses, which include both family lineage and a caste system, which provide leadership to the entirety of the Ascendancy. The Ruling Families are defined by blood relationships, but also include merit, in which one can earn his / her place within the family. Members of the Chiss military are known as Merit-Adoptives, and are “attached” to a Chiss Ruling House until they leave the military services. Some however do manage to become well known for their actions, may become “born to trial” and given the opportunity to become a full member of the house.

Family Hierarchy consists of brothers and sisters (or simply “siblings”), cousins, and ranking distant relations. The ranks of Aristocra and Syndic serve as high-level representatives of the Families.

The Chiss in SWTOR

Rumors abound regarding a secret base which the Chiss have set up inside the Republic. Evidence points to Hoth as being the location of that base due to the holonet entry for Hoth having the following Aurebesh hidden on the page.

CHISS SECRET BASE

Translation: Chiss Secret Base

Reference:

Wookiepedia