Su Yang had always felt that these people might be the reincarnations of those Land Immortals.
However, thinking carefully, that doesn't seem right. If it were reincarnation, maintaining the aura of the previous life is basically impossible. Moreover, reincarnation is already a very difficult thing, and such a large group of people reincarnating together is unlikely.
Later, Su Yang thought these people might be possession, but that also didn't make sense. So, Su Yang really couldn't figure out their situation. But the mystery of these people indeed perplexed Su Yang.
The assassins were said to be investigating this matter earlier, but later they got caught up in other things and had already left. According to Ye Sword Saint, the assassins could only return during the dark of the moon. Su Yang didn't know what they were busy with, nor whether they had uncovered the secrets of Liao Yuxuan and the others.