The Soul Calming Jade had protected Jun Gu flesh body by preventing it from rot and decay, allowing his corpse to maintain its condition as it was the moment just before he died. Once she finds Jun Gu's spirit, she would be able to let Jun Gu be revived!
And to find Jun Gu's spirit, she would have to go to the place that spirit bodies gathered, the Spirit World!
However, the demarcation of powers in the Middle Realm was extremely strange. The Dark Region sat in the most center of the Middle Realm and surrounding it were the Four Sides. The next outer layer was the Nine Temples' domain of power while the Twelve Palaces took up the area in the outermost perimeter.