This was because everything in the world complemented and countered each other. Once an enemy knew your origin, it was very likely that they could use your weakness to deal with you.
Even fellow disciples would not usually communicate about this.
Even the "longevity" disciple of the same sect did not know about Daoist Jade Cauldron's real identity.
That unlucky King Zhou, Di Xin, had even less of a chance to know.
Could it be that the identity of the Human Emperor's successor was only a disguise? Was this person also a remnant member of that era?
"Don't worry about how I found out."
"If you want to take back this tooth, bring me to the Fire Cloud Cave first!"
"In addition, the thing under the Nine Provinces Cauldron was also taken away by you, right?"
"Hand it over and this tooth will be yours!"