The inter-dimensional portal of foreign races was not unfamiliar to Ye Chen.
They constructed portals in the outer realm, then pierced through the void using these portals, creating a passage, and then opened the barrier to the Human Race World with another portal!
The larger the portal, the more stable the passage, allowing more warriors of greater strength from foreign races to pass through. However, this also generates more noise, making it easier for the True Martial Hall to detect the portal's aura and prepare defenses in advance.
Smaller portals create minimal noise, making it difficult for the human race to detect them quickly.
These details are recorded in the archives of the True Martial Hall.
