At the end of the Great Plague Era, most mortals had been forcibly relocated by cultivators to various pocket dimensions and small worlds.
However, the prohibition against simultaneously practicing both mortal and immortal arts grew stronger, and the cultivators couldn't escape their fate of mutually destructive conflict. The Immortal Gate was destroyed and the cultivation civilization also entered a prolonged period of darkness.
The so-called tide turns.
The number of cultivators drastically decreased, nearing extinction. But the mortals, like robust weeds, began to spring up from all over the world.
Regarding the origin of these newly born mortals, some people said that they were the ones who slipped through the net during the great migration campaign. Others suggested they were the descendants of cultivators. Some even said that mortals from small worlds had broken through the Immortal Forbiddance Formation and returned.