Jiu Juez, a cultivator of the Inner Core Skill, died a mysterious death, said to have been chopped into minced meat and scattered to the winds, by whom it was done remains unknown.
Before the "First Era" emerged, he had already been dispersed, and it's largely thanks to Jiu Juez's minced remains that many worlds were able to manifest a Transcendent environment.
Of course, the reason wasn't due to Jiu Juez himself, but rather because of the Inner Core Skill.
This inheritance was not some obscure or demonic practice; rather, it was a legitimate Heavenly inheritance. Even during Gu Shanhai's most glorious past life, this Inner Core Skill inheritance was considered top-tier, balanced and harmonious, with boundless prospects, pointing directly to the Saint Realm, and once acquired, one wouldn't need to switch cultivation techniques for a lifetime.