There were many forbidden regions in the continent of South Phoenix, but there was only one forbidden ground. And that was Forbidden by the Phoenix. It covered more than half of South Phoenix, and it was only because of the Mountains of Truth and other special reasons that it didn’t cover even more of the continent. Even still, it continued to expand year by year. In fact, many portions of it had already overtaken the Mountains of Truth. If things continued in this manner, then in a few thousand years, all of South Phoenix would be Forbidden by the Phoenix. 

One big difference between forbidden regions and forbidden grounds were the inhabitants. Forbidden regions usually contained beasts and grues. Sometimes they also had mysterious entities sealed in them. But forbidden regions didn’t produce intelligent species. Only forbidden grounds could do so.

One example of that was Forbidden by the Zombie in the Forbidden Sea. That was where the Seazombies had come to be, and it was why they lived so close to Forbidden by the Zombie. Similarly, there were species associated with Forbidden by the Phoenix. [1]

However, because Flame Phoenix was friendly...