Through Shang Ruqi's memories, Qiann Yan understood that this world was originally divided into two parts, completely separate, and that cultivators had to pay a great price to travel to the Mortal World.
And with no cultivation, it was impossible for mortals to enter the Cultivation World.
The Mortal World is low in spiritual energy, and cultivators won't come here to suffer unless necessary.
If not for the original soul being severely injured, reincarnation wouldn't have been chosen.
There's no guarantee where one will reincarnate. The original host was simply unfortunate enough to be reincarnated in the Mortal World.
To return from the Mortal World, one can use a Secret Technique with their soul to open a barrier.
It's much easier to open a barrier from the Mortal World to return, which is why Shang Ruqi kept suggesting letting the other leave.
