History

The borders of a kingdom were hard to define. There wasn't a strict measure like land or river in the vast space.

It's mostly empty with some star systems here and there. Stars and blackholes were useful landmarks. But they weren't of primary importance in defining a boundary either.

Why?

While stars and blackholes sound enormous and powerful enough to serve as permanent markers, they truly were not.

A rank 7 could easily 'move' a literal star from one location to another.

Even the awakeners in Sage avenue could do it, much less those with the powers of Matter and Energy.

In such case, the kingdoms looked for things that would not change easily. And they found the answer to lie in the structure of space-time fabric.

To be specific, space-time nodes.

These were specific points which behaved differently from their neighborhood in regards to the stretch of space and flow of time.