A Star Kingdom wasn't just simply a group of star realms under the rule of another star realm with more powerful beings. No, it was more than that. On a fundamental level, the star realm itself had to be powerful.
In the vast and boundlessness of Chaos, all stars were governed by the supermassive black holes at the center of the galaxies they orbit.
However, within the hundred million stars that orbited a supermassive black hole, groups could also form when stars achieve enough mass to draw other stars into their orbit.
The Skymagia Star Kingdom was one such star group due to the immense mass of its central star, the Skymagia Star, which had a hundred times more mass than the average star. As a result, it was able to attract a hundred vassal star realms to orbit it.
That said, the Skymagia Star didn't possess such immense mass at the start. It was only gained after swallowing other star realms.
This was also why Realm Wars were so common in Chaos.
