According to the celebrated Qel-Droma Epics, in the aftermath of the Cron Supernova's destruction of the planet Ossus, the forebears of the tribal Ysanna were a band of human Jedi who had survived.
Legend states that prior to the supernova's irradiation of the world, a contingent of Jedi sought sanctuary within the Crystal Caves situated beneath the Eocho Mountains. A small number of those who survived joined forces in order to endure the immense wasteland that Ossus had become. It is said that across the millennia, while non-human survivors are believed to have died off, the human survivors evolved into the Ysanna, the people who would eventually wander the wastes of Ossus and safeguard its remnants.