During that great cleansing, countless formidable figures stationed in the rear of the Myriad Sects were massacred. Although the cultivators of the Myriad Sects reacted swiftly at the time and were on alert, without their 'main combat power,' the Myriad Sects were utterly defenseless.
Thirty billion returning cultivators, along with the descendants of the Myriad Sects in the rear, were all driven into the Demon Realm by the second-tier sects, left to fend for themselves.
However, according to ancient records, it seems that there were two voices within the second-tier sects at the time. A group of powerful individuals tried hard to protect the descendants of the Myriad Sects, leading to internal strife, which gave the cultivators of the Myriad Sects a chance to survive.
