Iron Enclosure Mountain's terrain was exceedingly unusual.
Viewed from high above, the entirety of Iron Enclosure Mountain looked exactly like a vast, peculiar landform composed of concentric rings of mountains.
Those rings of mountains contained an extremely high concentration of iron and held vast deposits of hematite, so from the outside, many of the mountains throughout Iron Enclosure Mountain appeared dark red.
The circular mountain ranges were distributed with remarkable regularity. Across several million square kilometers of land, from the very center of the rings to their outermost edge, there were six circular rings of mountains in all. Each ring nested within the next, looking like the circles on a target.
With such a special terrain, its naming in military geography became simple and systematic.
From an aerial view, if Iron Enclosure Mountain was treated as an enormous clock face, due north was twelve o'clock, due south was six o'clock, due west was nine o'clock, and due east was three o'clock.
The innermost ring of mountains in Iron Enclosure Mountain was codenamed 1. The plain basin at the center of that ring, where humans and devils were locked in a fierce confrontation, was 0. Counting outward from the center, the second ring of mountains was codenamed 2, the third ring 3, and so on.
Finally, since the peaks of Iron Enclosure Mountain's circular ranges varied in height, some low and some high, adding a coordinate for a peak's elevation created a numerical code that could precisely designate any location within Iron Enclosure Mountain.
For example, Number 6403—the first six denoted the outermost, sixth ring of mountains in Iron Enclosure Mountain; four represented the four o'clock direction on the map; and zero-three indicated a mountain elevation of roughly 300 meters. Put together, the number referred to the vicinity of a main