Early hyperpower that developed around an abandoned wormhole nexus in the Hyades open cluster.
My breakfast finished with two things; an extra slice of meatshroom and a quarantine alert. I was tucking into the former when the latter came through. My apartment hermetically sealed itself faster than I could blink, let alone read the alert as it blazed across the wallscreen. "Citrine level quarantine is now in effect," announced the headline. Not the worst but then again not the best. All hab residents were strongly advised to seek shelter and remain until further notice. A curfew was not in effect (not unless the alert escalated to carnelian) but unnecessary movement was a risk to self and could constitute a violation of hygiene laws. I picked up my plate and walked over to the sole window of my apartment. A standard single-room unit it overlooked the central promenade that ran around the circumference of our toroidal hab. Normally it would be getting busy right about now but other than a few people hastily following yellow emergency strips it was bare.
The quarantine alerts had been coming more frequently lately. Not surprising really, we'd come to the Taurus Nexus some ten years earlier and in that time the number of craft arriving each year had grown exponentially. Everyone wanted a piece of the mysterious cluster of wormhole-connected systems. An unfortunate side effect was the sheer number of biological and nanotechnological passengers that hitched a ride. All systems have their fair share of rogue elements of both; incompatible, mutated or maliciously designed replicators that live in and around sophonts. With this new mixing of people previously isolated by light years of space, the spread of strains harmless to their hosts but lethal to others was more common, and more dangerous.
In 1558 AT the Wide Array Exotic Radiation Telescope (500AU baseline) in the SolSysOort Cloud detected unusual readings from Xi Geminorum (51 ly from Sol, class F5III). These energy and gravitational wave signatures were consistent with the existence of a wormhole in this system. Although the concept of hypothetical wormholes was well-known to cosmologists in this era, none had yet been detected. Since Xi Geminorum was sknown to have been colonised several hundred years earlier by Diamond BeltAhuman AI entities fleeing from the Solar System, it seemed likely that this wormhole was artificial in origin. Soon similar emissions were found from the stars Ain and Gamma Tauri, both stars in the Hyades open cluster. Observers surmised that these systems were all linked by some kind of wormhole network, which might extend to more stars in that cluster and elsewhere nearby.
An autonomous Explorer-Class probe ship the Carl Sagan was accelerated by Boostbeam to Xi Geminorum and arrived 120 years later, and reported the existence of a highly advanced AI civilization with many curious features. Attempts at closer examination and contact resulted in the destruction of the Carl Sagan by the AIs. This mysterious civilization was given the code name Xi Geminorum AI-1, and presumed hostile.
However, in 1931 AT, all indications of technological activity from the Xi Geminorum AI - 1 Civilization ceased, although the wormhole signatures remained. First Federation observers in the nearby New Callisto system suspected that this civilization had undergone a hyperbolic collapse or even a transaturation ascension, and launched a number of small fly-by probes towards the star. The results confirmed their suspicions. The megastructures associated with this civilisation remained, but there was no signs of activity such as waste heat or drive signatures, and the probes were not molested. The leading theory at the time was that the encounter between the Carl Sagan and the ahuman entities had somehow caused this disappearance event to occur, but the details have never been confirmed.
The Establishment of the Taurus Nexus
The New Callistans lay claim on the territory and began to tool-up for a massive colonization and development initiative. But word had long gotten out, and similar projects were launched from several other systems, including Federation, ex-Federation, and non-Federation.
Over the next three hundred years this network of 25 abandoned wormholes - now called the Taurus Nexus - was investigated and explored. Because the wormholes were all small (ranging from sub-millimeter to 10 meters, with a few nanogauge comm-wormholes) most transit was via nanoscale probes, uploaded mentalities, and microships equipped with engenerator technology. Even so, the Nexus rapidly developed into a hyperpower even more sophisticated than the Federation at its height. Sophonts of all types were attracted to the Nexus, and Transapient research into the still-functioning wormholes helped to advance their understanding of metric engineering considerably. The capital of the Taurus Nexus was established at Corona, Iota Piscium I, at the edge of the Inner Sphere.
After the decline of the First Federation, the Taurus Nexus became its apparent successor, considered by many to be the most powerful interstellar civilization yet created. Science mixed with hedonistic indulgence, libertarianism with aiviser guidance. Investment and technology flowed in from all over known space. Even the rise of the AI Gods elsewhere in the galaxy did not harm the Nexus, although there is no doubt that higher level subversion had a huge effect on local politics, and many bionts, cyborgs, vecs, and superturings clamoured to keep the Nexus free of foreign interference.
The Decline of the Nexus
After studying the abandoned wormholes thoroughly, the transapient combine Vega Geodesics managed to replicate the technology in 2110. Soon, new wormholes were being established throughout the Inner Sphere, and the Taurus Nexus came to seem hopelessly obsolete. From the 2500s onwards the original, small and often unstable wormholes were repaired or replaced by superior versions by weylforges designed by the Lord Of Rays. Foreign intervention and memetic engineering increasingly harried what had once been the jewel of the galaxy. In 3263 the "Inner Sector" attempted to break free in order to become part of the NoCoZo, leading to the First Consolidation War, one of the bloodiest early wars known. The surrounding empires annexed many of the worlds, and in 3400 there was not a trace of the Nexus.