There was a huge hollow in the middle of that sacred mountain in Castle of Black Iron. According to Heller, he renovated this place into a huge warehouse lest waste in basic energy storage.
Honestly, after Heller accomplished this space and topographical renovation, the basic energy storage of Castle of Black Iron almost used up. As a result, Zhang Tie had to carry the heavy responsibility to expand the basic energy storage for Castle of Black Iron.
Those items that Zhang Tie plundered from Tokei City were all in the hinterland of the sacred mountain.
