How is it possible?
On the Path of Yin Yang, several Ghost Kings awoke one after another, but before the great battle on the Path of Yin Yang could commence, they were horrified to find that their original masters... seemed to have mostly perished?
The Path of Yin Yang has always been a point of contention for all major factions every Era, even the Human World hasn't fought as fiercely as on the Path of Yin Yang.
There are several reasons for this.
First: The Human World represents the true strength of each faction, and if they fight hard against each other and suffer losses, it could genuinely affect the overall situation. Even with Elder Long's restraint, they can't start a fight, so the Path of Yin Yang becomes a good place for the real determination of winners and losers among the factions. Winning allows one to gain more resources and also lay more foundation for the next Era. Losing doesn't result in complete destruction, making it a de facto proxy war.