Astral People

The Astral People, also known as Astrals, were a presumably single species civilization that existed thousands of years ago, and were likely the first precursor to the modern Federation, thought to have been endowed with psychic powers and to have been explorers of the astral plane or native to it.

History
There are multiple theories as to how the Astrals came about, who they were, and their influence to later people.

Theory #1*
* This, IRP, does not quite exist yet, as it is meant to be a formulation of the autistic humans after the Federation sent them to infiltrate Earth.

The Astral People trace their origin back to a group of mixed blood Homo Magi residing within the Roman Republic who were pursuing their ancestors' experiments on spatial and temporal magics with funding from shady politicians and nobles, with the supposed end goal being to increase the Roman military's tactical and strategic mobility.

Fortunately for the impure magicians, the research was going well, and they organized tests for the spells they had invented. Unfortunately for them, however, two factors got in their way: their mixed blood, which hurt their innate magical power and instinctive understanding of it, and the unhappiness of the parties funding them, who had figured they were shit wizards (not inaccurate) and that they were getting nowhere (inaccurate).

Thus, on the faithful day of the first test, the wizards were sabotaged, and their low magical power led to them failing to adequately compensate. Due to circumstances unknown, the spell took effect regardless, and the impure Homo Magi were hurled backwards in time to a different planet.

There, they eventually realized that their low, but nevertheless still present, innate magical power was only going to decrease as generations passed, until eventually it vanished. Thus, the aliens abandoned their magics, focusing on other paths of knowledge and power. Eventually, however, for reasons unknown, the population started developing low psychic power -- maybe a result of latent magics, maybe a result of a metahuman gene put in their far removed ancestors by the Dominators triggering, maybe a combination of both, maybe they somehow gave themselves the power, who knows? The source of their psychic ability does not matter. What matters is their approach to exploiting it: "Psionics" as a scientific field arose, a consequence of their focus on non-magical paths of knowledge having originated a science-centered culture, and inevitably technology based on the field and exploiting their low psionic ability arose, leading to their discovery of the astral plane and the manipulation and alteration of it for their own ends, giving rise to such phenomenon, at least within the Federation and its immediate vicinity, as the Astral-Genetic Guide (or A.G.G.), thought to be a factor in the dominance of humanoid and near-humanoid sentient species and Self-Reality Imposition (or S.R.I.), a phenomenon in which reality is, usually briefly, rearranged to a subject's interpretation in a manner akin to mentifery.

Related to this theory, it has been proposed that the magic "shadow societies" within the Federation are far removed descendants of the original, impure Homo Magi and their traditions.

Biology
A successful reconstruction of what is thought to be an Astral was done by the Federation circa the 18th - 19th centuries AD (Terran time). From the reconstruction, it was extrapolated that the Astrals were very similar to humans and other near-human Federation member species, which is in line with other assumptions, hypotheses and discoveries on them, albeit more gracile, of skins with very faint yellow hues, and no body hair at all. Minor differences were detected between Astral skulls and the skulls of humans and near-humans, in particular proportions, overall size, orbit dimensions and chemical residues indicating differences in cranium and brain composition. Astral skulls were likely slightly larger due to a bigger neurocranium, and slightly more hollow, allowing for greater available volume for brains within their skulls than outside observation would suggest, and their orbits were larger, with slight differences in shape from the typically spheroid human and near-human eye, though, once again, not differences that would be noticed by outside observation. Chemical residues indicate alterations in make-up of the brain that are largely consistent with what is usually found in psychic species and psychic individuals. Another notable difference was the proportions of their hands, as they were unusually slender for human and near-human standards, but with slightly longer fingers. As the reconstructed Astral was a strongly androgynous, but very tall, male, it is thought sexual dimorphism was lesser in their species and that the average Astral was taller than the average human, although more individuals must be found before proper conclusions can be taken.

Science & Technology
Though much of their technological and scientific advancement is unknown, it is known that the Astral People treated psychic power scientifically and from it derived the ability to make "astral algorithms", artificial patterns imprinted onto specific sections of the astral plane akin to computer programs, which are responsible for things such as the Astral-Genetic Guide and the appearance of incomplete astral mentiferics, psychics with the ability to intersect the astral plane with our own and project their interpretation of reality onto what is, in fact, reality, in at least Federation & surrounding space, as well as to utilize the plane for travel and power supply.

Artifacts have been found that show extradimensional architecture/engineering that are thought to have been made by the Astrals due to etching commonly found on their work being present, but it is accepted that it could've also been the result of trade with other civilizations.

Society
Very little is known about Astral society, though it is theorized that they at least had historical periods in which they lived in excess in some way or another, if not always lived as such, which led to, or contributed to, the creation of the Horrors plaguing the astral plane's equivalent of Federation space, formed as the manifestation of concepts such as Lust and Envy.