Csilla, with a pronunciation of /ˈt͡ʃiːlə/, existed as a planet characterized by extreme cold and abundant ice, situated within the uncharted Unknown Regions. It served as the original homeworld for the sentient, near-human Chiss species and functioned as the primary capital for the Chiss Ascendancy. Largely obscured from the broader galaxy during the Galactic Empire's era, later exploratory expeditions into the Unknown Regions, occurring years afterward, unveiled Csilla alongside other reachable worlds through carefully calculated hyperspace routes.
Positioned at coordinates F-8 on the Standard Galactic Grid within the Csilla system of the Unknown Regions, Csilla was a frigid and ice-covered planet. Its main [city](/article/city], Csaplar, was largely constructed beneath the surface of the planet.
Regardless of whether they were Chiss or alien, visitors to Csilla were given the impression that the planet maintained a vibrant population, despite the significantly colder climate. The areas surrounding the Csaplar spaceport were lively, featuring hotels, entertainment venues, merchants, diplomats, and government and military operations. However, most above-ground sections of Csaplar and other cities were intentionally kept devoid of permanent residents, designed to merely simulate the appearance of a densely populated world.
Near the end of the Clone Wars, approximately 60 to 70 million Chiss still resided on Csilla. The great majority lived in illuminated and heated underground caverns, which even contained forests, lakes, mountains, and realistic artificial sunlight. To uphold the illusion of a population of 8 billion, a selection of these underground residents were chosen on a rotating basis to spend brief periods on the surface, creating the impression that they lived there permanently.
For millennia, the Chiss inhabited Csilla, spanning thousands of years. Around 1000 years prior to the Clone Wars, during the final stages of a major war between the Chiss Ascendancy and an enemy, the Chiss were compelled to retreat to Csilla. Despite previous setbacks, the Chiss Ascendancy had no choice but to deploy an ancient alien weapon known as the Starflash. The sacrifice of all four sons of the Mitth Patriarch Thomoro resulted in the complete destruction of the enemy force, preventing the Ascendancy from being conquered and elevating the Mitth family to a position among the Nine Ruling Families. However, the weapon also had an impact on Csilla's sun, causing it to cool down and rendering the planet's surface uninhabitable.
Due to the shift in temperature, the vast majority of the planet's four billion inhabitants relocated to the planets Rentor, Avidich, and Sarvchi. The remaining population moved underground. During the Clone Wars, official records indicated a population of eight billion on Csilla, but the actual number was closer to sixty to seventy million. To sustain the appearance of a thriving planet, several hundred Chiss citizens were stationed near Csaplar's spaceports, and tube cars were continuously operated throughout the empty city.
Csilla was openly targeted in 19 BBY. Three unidentified enemy capital ships materialized from hyperspace and launched an assault on the orbital defense platforms. The defenders, initially surprised, responded with fire within a minute, successfully destroying all three ships and any resulting debris to prevent damage to the planet. All leadership on the planet retreated to underground bunkers and remained there for several hours to monitor for any subsequent attacks.
The Chiss and their home planet were largely unknown in other regions of the galaxy. As a result, when an Imperial scouting party, under the command of Captain Voss Parck, encountered Thrawn around 15 BBY, Parck tasked cadet Eli Vanto with gathering information from the alien about his species and homeworld. In 4 ABY, the Force spirit of the Jedi Obi-Wan Kenobi informed his apprentice Luke Skywalker that the destiny of Csilla, along with many other planets, depended on his confrontation with the Sith Lord Darth Vader during the Battle of Endor. Following the Battle of Crait in 34 ABY, the pirate Hondo Ohnaka included Csilla in the galactic map featured in his book, the Galactic Explorer's Guide. Despite the limitations on exploration of the Unknown Regions due to hazardous hyperspace anomalies, occasional exploratory missions into the region by 35 ABY revealed several navigable worlds—including Csilla, Ilum, and Rakata Prime—accessible through carefully executed hyperspace jumps.
Csilla, a component of the Chiss Ascendancy, was the original homeworld of the sentient Chiss species.
At some point, an artist journeyed across the galaxy, documenting the Chiss and their capacity to thrive on icy planets within his journal. This document was later restored and published by the Graf Archive sometime after 34 ABY, featuring a mention of Csilla as the Chiss homeworld.
Csilla was initially referenced in the new Star Wars canon on a map within the 2016 StarWars.com article titled Where in the Galaxy Are the Worlds of Star Wars: The Force Awakens?. Csilla made its first canonical appearance in Timothy Zahn's 2020 novel, Thrawn Ascendancy: Chaos Rising, which served as the inaugural installment in Star Wars: The Ascendancy Trilogy.