The Utopia was a ancient civilization that ruled over almost all of Amoeni Space before life re-emerged. They were founded by an unknown species (given the name 'Utopials'), on an unknown world, (given the name 'Utopia Prime').
The Utopia was founded on an unknown world, designated 'Utopia Prime'. At the time, it was a lush world with retinal-based vegetation, as well as a temperate climate. For an unknown reason, it was not as severely effected by the Aeternum Event, so life rose quickly again.
Extremely quickly, The Utopia spread out until at their peak they controlled 99.999997783% of Amoeni Space. However, they stagnated. The solved every possible problem they could, bringing their lives up to maximum pleasure and minimum pain, as well as mitigating all selfishness, hate, hurt and pain from their citizens lives. However, they had no goal. Slowly, their science stopped advancing and even began to retreat in some cases. Eventually, the civilization crumbled away as their citizens lost the will to live with their eternal lives.
The Utopia covered the entirety of Amoeni Space, functionally. With billions of worlds, trillions of megastructures and so many people the individual becomes meaningless, they were among one of the largest civilizations every known to the entire cosmos.
Tarmalyula was their home galaxy, their galaxy of origin. Because of this, their activities were mostly centred here, as well as their government, what little of it that could be found. Tarmalyula is also where their species came from, its fertile nebulae birthing The Utopials.
The Lance Galaxy was not very interesting at the time. Holding an approximated 9% of the entire nation, and providing next to no GDP, Lance was the sinkhole of The Utopia's recourses. The Lance Galaxy was the figurative backwaters of The Utopia, having the most loosely controlled population and recourses.
The Eucliar Galaxy was The Utopia's home away from home. Holding many worlds ripe for terraformation, Eulciar came to hold 34% of the entire nations population, therefore making it a hub of trading and construction. This also explains the large amounts of Rifts present in the galaxy.
The Utopia has influenced the Utopial values of most present nations in Amoeni Space. Without them, we probably would've seen a large influx of powerful imperialistic civilizations warring across Amoeni Space. Another major thing that the Utopia is responsible for is the life in Amoeni right now! They terraformed and manipulated billions of worlds to play host to complex multicellular life, probably being responsible for one in three civilizations birth. Without the Utopia, Amoeni probably would be less vibrant and lively.
If the Utopials knew how to do anything, it was to build. Covering the entire of Amoeni Space are networks of Rifts, linking parts of space to other parts of space that they probably wouldn't have seen without them. The Utopia also constructed millions of megastructures, which the majority of which probably have decayed over time. However, ruined megastructures are very common throughout Amoeni, providing huge boons to the nations of Amoeni.