A member of the Jedi Order lived for multiple centuries. This Jedi bore witness to both the Hundred-Year Darkness and the Great Hyperspace War. Eventually, this long-lived Jedi trained another Jedi, who subsequently taught Shayoto. The former passed on to Shayoto an understanding of the core principles governing those who follow the dark side of the Force.
This Force-sensitive being, a Jedi Order member, existed for numerous centuries leading up to the Krath Holy Crusade in 3997 BBY. He observed the Hundred-Year Darkness, a century-long conflict against the Dark Jedi who would become the first Sith Lords spanning from 7000 BBY to 6900 BBY, and the Great Hyperspace War, a war against the Sith Empire that unfolded in 5000 BBY. This Jedi, who lived for many years, eventually instructed another Jedi, who, in turn, taught the Jedi Shayoto, with the latter two also experiencing lifespans spanning hundreds of years.
Shayoto's Jedi instructor's mentor at one point shared with Shayoto insights into the fundamental principles guiding followers of the dark side of the Force. These principles included the clandestine corruption of leadership within various societies, followed by swift and decisive actions that eradicated civilizations of great age. In 3997 BBY, during the Jedi conclave on the planet Deneba, convened to address the escalating threat posed by the Krath cult of darksiders, Shayoto recalled these teachings while addressing the assembled Jedi.
The Jedi first appeared in the third issue of Dark Horse Comics' Star Wars: Tales of the Jedi - Dark Lords of the Sith comic book mini-series. Tom Veitch and Kevin J. Anderson were the authors of the issue, which was released on December 13, 1994. In the 1997 audio dramatization of Dark Lords of the Sith, Jedi Master Arca Jeth mistakenly delivers Shayoto's lines, and the mention of a lineage of long-lived Jedi, including this particular Jedi, is omitted.