The Future Realm was separated from the outside world by the Spatial Storm. Still, the realm itself was gigantic, no less than an average country. However, that wasn't what made this a cultivation heaven. Instead, one of the reasons was the resources.
Because it was cut from outside, and the number of experts who could enter was highly limited, there was plenty of time for cultivation resources to grow and appear. You could say that this was almost an inaccessible Divine Stone Mine, Herb Garden, Divine Mineral Deposit, and so on. Even the concentration of Divine Energy and Divine Origin Energy was higher as a result.
The second reason was definitely the Temporal Plates, which connected to other possible futures and affected the realm itself. In a certain way, you could say that the Future Realm was the Chronoblade Serpent's Domain, just like Rean's Life World Domain or Roan's Death World Domain.
