SUMMARY
Sometime prior to the end of the Human-Forerunner Wars, ancient humans discovered a Precursor stasis chamber containing a creature they called the Primordial. The creature, along with the stasis chamber, was taken to Charum Hakkor where is was interrogated, teaching the humans on the origins of the Flood. Many humans were so horrified by what they learned from the Primordial, they committed suicide. Following the end of the Human-Forerunner Wars, the Primordial remained at Charum Hakkor until its release around 98,000 BCE during the Test Firing of Installation 07.
RELATED MEDIA
These events are referenced in the novel Halo: Primordium, which was the subject of a Halo Book Club on September 23rd, 2016.