The Orion Sphere is littered with the relics and ruins of bygone civilizations. Although these remnants are relatively common, the vast majority are nothing more than a few scattered ruins, long emptied of technology or any trace of the society that created them. Precursor remains can be thousands or even millions of years old, and a rare few contain lost secrets or troves of advanced technological artifacts.
Precursor sites can be found in almost all conditions and areas of known space. Abandoned orbital stations circle ancient, dying stars, cyclopean ruins can be found in secluded areas of life-bearing planets, and hulking monoliths lie undisturbed on dead, airless moons. Although these remnants bear silent witness to countless species and empires across time, no known extant species developed spaceflight more than ten thousand years ago. Some ruins have been dated as being hundreds of thousands or millions of years old, but even in the legends and myths of the oldest surviving species there are no records of encountering their creators alive.
The majority of Precursor sites are one-off - singular monuments to their long-extinct creators. There are some, however, which can be linked by design, energy signatures or indecipherable scripts as having a similar origin. These linked relics and sites are thought to represent the only physical remains of long-dead Star Empires - the Factions of whatever ancient time they occupied. New information and sites are regularly discovered, and the community of deep time researchers is constantly trying to fit new finds into a rough chronology of our galaxy, rarely with any success.
Some of the more well-cataloged Precursor civilizations are detailed in the links below;