Taarja was a trade language used for communication across the galaxy. Around the time of 34 ABY, Ungrila Yasto Attsmun spoke Taarja while aboard the yacht Undisputed Victor. The yacht was departing Canto Bight on the planet Cantonica.
To communicate with the Paccosh during their Mission to the Rapacc system circa 19 BBY, the Chiss Ascendancy utilized Taarja. Although she could speak it, Chiss caregiver Mitth'ali'astov did not enjoy using Taarja. She characterized the language's sounds as "angular." During several confrontations, the Kilji species and the Grysk "Jixtus" employed Taarja to converse with the Chiss. The Taarja term for "instructions" also encompassed the meanings of "suggestions" and "orders," a fact that Qilori exploited to irritate Kilji General Crofyp while serving on the Kilji war cruiser Anvil.
Taarja's first appearance in Star Wars canon was in the 2017 movie Star Wars: Episode VIII The Last Jedi. It was initially identified in the "Every Language in Star Wars Movies" video from Star Wars By the Numbers, which was uploaded to the Star Wars Kids YouTube channel in 2019.
Within the Star Wars Legends continuity, Taarja was a trade language that initially featured in Timothy Zahn's 2006 novel, Outbound Flight.