"Anti-spirit Material"
This experiment already violated the taboo of experimenting with intelligent beings, but the world union dared to do this behind everyone's back!
There were even plant civilizations here, similar to druids, but they didn't have a humanoid form like the druids, which was why they became a small civilization that no big 7 races wanted to take in.
The 7 big races all had humanoid forms, and even the rare races attached to the 7 big races also had humanoid forms, such as druids, golems, stone men, orcs, goblins, or gnomes.
On the contrary, the races locked up here for experiment didn't have a humanoid form, and so, even though some of them were popular races mentioned in many fantasy novels and stories, most people didn't think these races really existed.
Even now, many human beings, especially those who were not ability users, were ignorant of the non-human races living outside of the human continent.