“Phage” is one name that many civilizations have used to describe the failed civilization that is now no greater than a Cargo Cult (and perhaps not that much). The people of Phage have nothing to do with the “civilization”. Indeed, there is no real civilization. Instead, there is a self-replicating infrastructure that spreads from world to world, and a symbiotic (or perhaps parasitic) set of intelligent components, including artificial sapience, human intelligence, atavist genomes, uplifted and semi-uplifted animals, and a host of other incidental beings (perhaps including true xenospecies intelligence), and the two sets really do not directly interact with each other.
In essence, Phage is a hive. Not a “hive-mind” (which, in truth, is a Group Mind), but a true hive. The individual components of the hive don’t really think about supporting the hive (most Phage organisms do actually contemplate their support of the hive if they are intelligent enough to do so, but mostly in abstract philosophical terms no more definite than other “similar” questions like “why are we here” or “what is the meaning of life”). Each component, by behaving in its own natural way, contributes to the hive without truly needing a decision making process to do so.
Phage, thus, is a Van Neumann construct on a massive macroscale, spreading from world to world on womholes that it finds or constructs (despite the fact that few to none of the composite intelligences actually knows how to do that) to occupy new expanses of habitable or at least useful regions, forming a massive distribution (referred to by scholars on the matter as the “Swath” or the “Phage-Swath”). When it encounters a new element, be it a specific technology, a new Civilization or Society, it integrates that new agency (often causing its devolution in order to fit it into the hive more properly), pushes it away, destroys it entirely, or is rebuffed by it.
So far, despite the comparatively primitive nature of all the composite intelligences of Phage, no efforts have successfully sterilized it. It is an insidious threat, like an army not marching to the beat of the drums, a cancer slowly rewriting the face of the galaxy into its own pseudoheterogenous image.
There are technically several cargo cults and other forces at work within Phage. Thus, while this is described by many as “a Cargo Cult”, use of that turn of phrase to describe Phage produces fabrication at a ratio of at least 1.5 inveiglements per word.