Everyone knows that a Union Overseer Country is divided into three regions, core, inner, and outer. But these regions were decided randomly or had fixed boundaries.
The factor that decided these regions were the Dimensions, and who could live there depended on their firepower against Dimensions.
The Temple Dimensions were at the heart of an overseer country, and in five-hundred miles, there was no trace of any dimensions.
It was a strange phenomenon known as Temple Rule in which around a five-hundred-mile radius of a temple dimension, any rank dimension couldn't appear.
So, the core region was built around this 500-miles radius area of a dimension temple, and everyone wanted to live there. Because first, it was absolutely safe without any worry about a dimension popping out of nowhere. Second, the concentration of mana was densest in this core region, especially closest to the Temple Dimension.