The Azure Mystic Immortal Realms was a real world of the immortal realms. Around this region were countless particle worlds. There were also an endless number of experts belonging to an uncountable number of powers. Within these powers, the most famous ones are naturally none other than those who stood at the peak.
Countless years ago, immortals, demons and devils were well-distributed across the vast immortal realms. But eventually because of the differences in their philosophies, conflicts soon erupted. And as time passed, this layer of the immortal realms which was known as Azure Mystic, began to be divided up. Right now, the human cultivators occupied the majority of the land. Devil cultivators relocated to the similarly boundlessly vast Devil Myriad Islands while the demonic beasts all moved to the Western Region or the Ten Thousand Desolate Mountain Range, only communicating with each other if needed; However, devil cultivators were still devil cultivators. They shared many similarities with demonic beasts, their innate dispositions were violent and warlike, all of them incredibly dangerous. It was said that under the Devil Sovereign who ruled over the Myriad Devil Islands, cruelty was the path to the strong. The weak died while the strong survive.
Although it has declined, it was once glorious before. After that war countless years before, somebody imposed a ban on Azure Mystic, forbidding all empyrean-level characters from entering. The various superpowers were all reluctant to accept this. From what I know, through these countless years, they have never stop their probing of the Azure Mystic Immortal Realms.
There are no rankings among the thirty-three heavens. All of them are cultivation grounds. It's just that the Azure Mystic Immortal Realms are a little unique. They are sealed off from the others. And the reason why was because, there's someone who doesn't allow the people of the Upper World to enter this place.
Naturally, that existence wouldn't obstruct those at the emperor realm and below to enter. But those people might not have enough strength to take over this immortal realms without support from the respective superpowers they are from. That existence didn't forbid those who left here from returning. As long as you can return, you will be able to return.