Initially, people from the Cultivation World went to Earth to capture the Prophecy Girl and incidentally also took a number of men with potential or other uses captive.
For example, Feng Tianyou, Hong Yan, Duan Qingcang, and others all disappeared during that period.
Xiao Chen thought, considering the Immortals Palace's attack on the Spirit Race to seize the prophetic heavenly book, the prophetic heavenly book must be in the hands of the Immortals Palace.
This meant that the ones who had instigated the Cultivation World to capture the Prophecy Girl were also from the Cultivation World.
Similarly, after the Blood Shadow Sect captured a large number of captives, the mysterious people who attacked the Blood Shadow Sect and took away all the captives were also from the Immortals Palace.