When Cain started looking into the phenomenon that had led to Port Nefheim being attacked, he found that it was actually much more widespread than anyone had suspected. On the Southern Continent, it was impossible to track them, since the people stuck in the Vortexes had similar stories, but these outliers were from a much earlier time. For the most part, they arrived right after the Human Gods were defeated by the Pantheon of the Creators, which included the Laughing God.
The only ones that seemed to be arriving were the human soldiers though, ones with a connection to Divine Energy, though Cain heard a few possible reports of Beastkin Clergy who worshipped the old ways arriving as well. Ironically, it was his own Guild that made those ones hard to verify.
