Seven-hundred and eighty years before the events of Radiant Dawn, Ashera, the goddess of order, decided to destroy her counterpart Yune, for she thought Yune blemished her perfection and the peace in the world. However Lehran, Ashera's closest consultant, asks her not to do so, and to instead seal Yune into a bronze medallion instead. Ashera finally agrees to his counsel, under one condition. That if there were no war on Tellius for the next 1000 years, she would allow Yune to be freed and to reunite with her. However, if the Beorc and Laguz are not able to keep the peace for this time, Ashera will destroy the existing world immediately. However, if she were to be waked instead by the Galdr of Release, she promised to first have counsel with Yune before acting. To stop the Beorc and Laguz from warring, Yune is later said to be a dark god, who will destroy the world if it wakes.
Several years before Path of Radiance, Mad King Ashnard obtains Lehran's Medallion and plans to pitch Tellius into war by freeing the "dark god". To do so, he kidnaps Lillia, a heron princess from the clan of the Serenes, to sing the Galdr of Release. He keeps her locked in a windowless room in Palmeni Temple, where Elena sees to her well-being. However, Lillia is unable to release Yune from the medallion, as her powers have faded due to exhaustion. Lillia then passes the words, melody of the Galdr, and the Medallion to Elena and eventually dies in the Temple due to her bad condition. Elena then leaves Palmeni Temple, with a plan to bring the Medallion safely back to Serenes, but she and her husband Greil have to flee from the Daein army for several years, and finally find refuge in Gallia.
Greil unintentionally touches the Medallion and it drives him to complete madness, until he ends up killing Elena. As hinted at when Ike was little he was scolded harshly by his father for attempting to touch the medallion. If one touches it, the Medallion magnifies the worst aspects of a person a thousandfold. The proportion of order and chaos within a person also changes the effects of the Medallion on the person who touches it. Only people who have order and chaos in complete balance are able to touch it unaffected. Mist and her mother Elena are the only Beorc known to be able carry it safely, while the Heron royals also can do so. After Elenas death, Mist inherits the Medallion from her, though believing it to be only an ordinary medallion. However, at the end of Path of Radiance, Mist learns about its true qualities.
In Hard and Maniac modes in Path of Radiance, Ashnard touched Lehran's Medallion after Ike defeats him the first time and somehow retains some portion of sanity.
In Radiant Dawn, during the finale of part 3, the chaotic energy of the medallion increases due to the fighting, until eventually Mist, Reyson, Rafiel and Leanne collapse. Mist advises to wake the dark god with the Galdr of Release instead of doing nothing, so Micaiah, at this moment already possessed by Yune, sings the Galdr, and Yune is freed. Although Ashera promised first to discuss her plans for the Beorc and Laguz with Yune, she immediately judges them by turning almost every single inhabitant of Tellius into stone. Yune and the remaining, spared by the judgement decide to face Ashera in the Tower of Guidance.