From Halopedia, the Halo wiki
During the protracted war on Installation 00, the Unggoy Yapyap served as a soldier in the Banished. At some point in the conflict, Yapyap was able to recover the crown of the late-Prophet of Truth - who had been killed by Thel 'Vadam in the Ark's Citadel some seven years prior.
With this artefact in his possession, Yapyap used it to make a claim for leadership, with his continued shows of independence and bravery inspiring numerous other misfits and malcontents within the Banished to join him. Yapyap made his seat at a location known as the Throne of Woe, and began to lead his forces - inspired by a probable-lie told by a Kig-Yar fortune teller - to locate the fabled Golden Methane Hydrate Mines of Sabator.
While actively rebelling against the Banished, Yayap's follies were tolerated by Atriox for a time, as his expeditions into hitherto-unexplored regions of the Ark proved useful - with the rebellion's forces taking the brunt of the fire from the Ark's errant Sentinel defensive networks.
Following Atriox's departure from the installation, Let 'Volir succeeded him as the commander of the Ark's Banished forces. As such, 'Volir is unlikely to continue to allow Yapyap's rebellion to continue to act with impudence for much longer.
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