The T'Syriél were a race of towering, well-built humanoids who originated on the planet called Shiva IV. These beings were organized into the Twelve Tribes of T'Syriél, and for countless years, they engaged in conflicts with the Human Calian Confederacy, ultimately shaping a formidable and respected martial culture. However, in the year 2 ABY, these long-standing conflicts came to a close with the signing of the Concordat of Peace. Despite this, many disgruntled T'Syriél were later exploited as soldiers during the Imperial General Bentilais san Sk'ar's attempt to seize control of Shiva IV.
During the time of the Galactic Civil War, the T'Syriél society was structured around the Twelve Tribes of T'Syriél, each governed by a leader known as a Demarch. Nevertheless, a considerable number of T'Syriél existed outside this tribal structure, often forming bandit groups that roamed the planet's desolate regions. The T'Syriél possessed a distinguished warrior heritage, a result of generations of warfare, although this tradition had begun to wane somewhat by 3 ABY.
The T'Syriél engaged in prolonged warfare on Shiva IV against the Human inhabitants of the Calian Confederacy, with the constant fighting shaping them into formidable warriors. This era of conflict concluded in 2 ABY, when the Demarch Kéral Longknife and Calian Warlord Aron Peacebringer signed the Concordat of Peace, leading to an alliance between their peoples. However, this treaty did not resolve all of the T'Syriél's problems. In the following months, many T'Syriél outcasts abandoned their honorable traditions and lost the spirit that had made them such formidable fighters.
In 3 ABY, Imperial General Bentilais san Sk'ar, a Kaleesh tasked with conquering Shiva IV for the Empire, recruited a number of T'Syriél outcasts. Sk'ar strategically employed T'Syriél and Humans to sow discord between the Twelve Tribes and the Confederacy, creating the illusion of betrayal on both sides. During Sk'ar's attempted takeover, some T'Syriél fought wearing specially modified stormtrooper armor. Ultimately, Peacebringer, Longknife, and elements of the Rebel Alliance joined forces to thwart Sk'ar's scheme.
The T'Syriél made their debut appearance in Star Wars (1977) 53, written by Chris Claremont and published in 1981. Much of the artwork featured in Star Wars issues 53 and 54 was originally created for Marvel Comics' John Carter, Warlord of Mars series, which was canceled in 1979. Marvel decided to repurpose approximately 30 pages of fully-penciled artwork by having artist Carmine Infantino adapt the pages for Star Wars, transforming the Martian natives into the T'Syriél.