Jedarians and Sethians
Before the molecules of Coruscant were forming, before the Corellian sector was formed, before there were even medichlorines, there existed two species: the Jedarians and the Karistan (known as Sethians to the Jedarians).
Both species were aware of the existence of a power within that resided with all living things, which the Jedarians referred to as Horla (hor - powerful, physical, living; la - perception, connection), yet they disagreed on how to use it. The Jedarians, peace lovers by nature, thought it wiser to first to control one's own self before controlling this power, to fuel it with peace and live their lives with honor. But the Sethians, who did not agree in holding one's self back, used anger and fear to fuel this power and used it for their own purposes.
Both species lived as far away from the other, keeping the other at great distance, fearing the other would influence their own species away from their own ways. But, like all other things, conditions must change and then the new must come. Both species started to notice other species that were evolving and forming cultures (such as Humans, Mon Calamari, Rodians, Gamoreans, Twi'leks, Bothans, and others).
To the Jedarians, these new ones were being just as capable with the mind and Horla as any Jedarian. To the Jedarians, these species were equals, and treated them as such, leaving them to create their own technology, culture, and history. Yet to the Sethians, the new ones were viewed as slaves, ripe for the harvest.
Jedarians were a rather patient and tolerant species toward other ways and customs, yet they drew their lines. When news had reached them that the Sethians had not only taken over these people as slaves, but also slaughtered some just for sport, it was clear that the Sethians had crossed the line.
Rescuing whomever of the new ones that they could, the Jedarians took it upon themselves to teach their newfound friends of Horla in order to help, fight, and defend - to fight the evil and liberate the needy. Gathering habitable planets from various systems, the Jedarians created a single system for a refuge for those of the new ones who could not fight, with a space station for protection. Rallying what help they could, the Jedarians fought back the Sethians till nothing of the Sethian ways were left.
With the Sethians gone, peace came once more, yet the damage had been done. Contrary to leaving the new species alone, to let them build and learn on their own, the Jedarians had introduced technology beyond their comprehension; integrated all types of intelligent species before their time, and had taught them of the force and power within each and everyone person. The Jedarians also created what was not natural and not to be - an entire system out of planets from different areas of the galaxy, with two twin planets revolving around a giant space station. Taking all that they could, the Jedarians built a new home for all of the new ones, spanning all across the galaxy. The last thing they left was their order of peace and Horla. That was their last gift to the new ones. With that, the Jedarians all secretly gathered together in one remote star system, disappearing from the known galaxy.
Over time, the new ones forgot about the Sethians and thought of Jedarians as only angels in children stories, until those stories disappeared as well.