ur-Kittât, more widely recognized as Sith or the Old Tongue, represented the runic language employed by the Sith. It functioned as a clandestine means of communication among members of the Sith Order and the Sith Eternal cult, documented through a distinctive runic form.
The Sith were the original speakers of ur-Kittât. It was commonly found decorating temples, for instance, the Sith Citadel situated on Exegol, and their obelisks, such as those located outside of the Malachor Sith Temple. Inscriptions were also present within the tomb belonging to Darth Bane and the Lothal Jedi Temple. Furthermore, the language served a purpose in Sith rituals. A cult known as the Ascendant, who were captivated by replicating the effects of the Force using technology, recited a mantra in ur-Kittât.
On the planet of Lanupa, ur-Kittât inscriptions were visible on the walls of the Mud Pits found at the Skull Ridge Mountain Hotel & Spa.
In an attempt to isolate Sith worlds and eliminate Sith history, the Galactic Republic deemed ur-Kittât a prohibited language, leading its Senate to enact legislation around 1000 BBY that restricted droids from translating any writings in it. Despite this restriction, the Sith persisted in their use of both ur-Kittât and its Balc dialect. Some Jedi also possessed knowledge of how to interpret and speak the language.
By the reign of the Galactic Empire, ur-Kittât became known as "the Old Tongue" or simply "Sith." Nevertheless, it remained in use by Galactic Emperor Darth Sidious, who passed it on to his apprentice, Darth Vader. During the Imperial Era, Sava Iglan'tine Nos taught the Ascendant Mantra at the University of Bar'leth, tasking her students with translating it from ur-Kittât into Galactic Basic. Nos considered Kho Phon Farrus, an archaeologist, to have produced the finest translation in her class.
Later, the language was inscribed onto a dagger that held the coordinates of the Emperor's wayfinder, ultimately leading to the discovery of the hidden Sith world of Exegol.
Following the destruction of Kijimi, Beaumont Kin translated Darth Sidious' Sith language across all frequencies as he proclaimed, "The Resistance is dead. The Sith flame will burn. All worlds, surrender or die. The Final Order begins."
Typically, ur-Kittât was written using runes. The written form had a number of variations, as demonstrated by the ancient text that Ahsoka Tano translated outside the Malachor Sith Temple. The meaning of specific words and sentences could be altered by changes in line spacing, breaks, and inflection. The Sith Eternal inscriptions concerning the prophecy of the Force dyad between Ben Solo and Rey bore a close resemblance to the inscriptions that described the Rule of Two.
While runic scripts were the most prevalent forms of written ur-Kittât, not all Sith possessed expertise in this system. Consequently, some practitioners resorted to transcribing their alphabet into reflected Aurebesh characters, readable only in reverse. During an expedition by the Lerct Historical Institute in 21 ABY, archaeologists unearthed an ancient Sith holocron inscribed with this system.
The Sith language has its origins in the Star Wars Legends comic-book series Star Wars: Tales of the Jedi, which was published in the 1990s. During that time, the language was formed of nonsensical words, consisting of unpronounceable consonants. In November of 2010, senior editor Ben Grossblatt, who holds degrees in linguistics, developed the modern, functional Sith language for the publication Book of Sith: Secrets from the Dark Side.