Essentially speaking, there is no very clear boundary between the immortal realms created by the Human race.
Even if there were, it would be man-made.
For example, between the immortal realm where Wei Cheng and his group currently were and the Autumn Immortal Monarch's realm, there was an extremely ancient beacon that could be ignited with Dao Fire.
It was crafted by the alliance of the Bai Xi Celestial Monarch and the Autumn Immortal Monarch, using their immense Divine Powers.
This beacon could be considered the starting point of their respective expansion into immortal realms, the original bridgehead.
Now, Wei Cheng and his party were trudging beneath this massive beacon.
They were very close.
But the difficulty was increasing.
Countless vines and branches entangled them, covering their bodies; from a distance, each person looked entirely green.
But no one dared to tear or cut these vines and branches; they let them wrap around freely.
This was Wei Cheng's command.