The Grand Cyclic Stellar Region was originally a grand cosmic territory that contained hundreds of thousands of starfields, its territory divided and vast, filled with a variety of life and mysteries. However, as cultivators developed in strength, numbers, and technologies, the number of starfields were reduced.
Some of the Solar Stars met their ends at the hands of Ascended-level Wars. Others were taken to serve as a foundation for secret realms, world realms, or additional suppliers of essence for cultivators. A few were taken away and forcefully merged with other solar stars, creating super-sized solar stars that could even engulf multiple starfields.
The Aeternal Sky Starfield was one such example. Their supermassive Solar Star was orbited by a Mystic Radiance Belt and served to provide the entire starfield, which was the result of hundreds of starfields merging, high-leveled essence.
Originally, I planned for the Aeternal Sky Starfield to be the only starfield with a Mystic Radiance Belt. Later, I realized this wouldn't make much sense as the other powers have Ascended and even Earthly Saints, so I rewrote it to make more sense relative to our amazing world.
The Aeternal Sky Starfield has a Supermassive Variant. The size of which could be a thousand times the size of the others. This settled a few things. Such as the question: Were the Mystic Radiance Belt in the Aeternal Sky Starfield the first? No, but it was the first megaproject!