Early hyperpower that developed around an abandoned wormhole nexus in the area of space bounded by the Pleiades and Hyades.
In 1558 the Wide Array Exotic Radiation Telescope in the SolSys Oort Cloud (500AU baseline) detected unusual readings from Xi Geminorum then, 51 ly from Sol class F5III. Energy and gravitational wave signature matched the artificial wormholes detected around the apparent Diamond Belt colonies of Nu Tauri (150 ly from Sol class A5V) and Omicron Orionis (also 150 ly). The amat-powered research vessel Carl Sagan was dispatched to Xi Geminorum and arrived 120 years years later to discover a post Diamond Belt hyperfast ai civilization creating a distributed megascale intelligence. The civilization was given the code name Xi Geminorum AI - 1. Attempts at closer examination and contact resulted in the destruction of the probe by local defenses
In 1931 instruments at New Callisto, the nearest large hu-inhabited polity, ceased to detect signals (apart from wormhole signatures) from the Xi Geminorum AI - 1 Civilization. After hastily running through a number of simulations the Newcallistons suspected the civilization had transcended or undergone a hyperbolic collapse, and launched a number of small probes. The results confirmed their suspicions. The megastructures remained but there was no activity, and the probes were not molested. The Newcallistons 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 other systems, including Federation, ex-Federation, and non-Federation.
Over the next three hundred years the network of wormholes - now called the Taurus Nexus - was colonised. Because the wormholes were all small (ranging from sub-millimeter to 10 meters, with a few nanogauge guide and comm wormholes) most transit was via nano-assembler, uploads, and engenerator microships. Even so, the Nexus rapidly developed into a hyperpower many orders of magnitude vaster than the Federation at its height. Sophonts of all types were attracted, and research on the functioning wormholes helped advance hu and SI:1 technology. The capital of the Taurus Nexus was established at Corona, Iota Piscium I, at the edge of the Inner Sphere
For almost a thousand years the Taurus Nexus was the greatest and most magnificent empire mindkind had ever seen. Science mixed with hedonistic indulgence, libertarianism with aicratic guidance. Investment and technology flowed in from all over known space. Even the rise of new toposophic ai 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 superturingrade ai conjured nostalgic visions of the Nexus free of foreign interference.
As more advanced and sophisticated wormhole nexi were established elsewhere, the Taurus Nexus came to seem hopelessly obsolete. From the 2500s onwards the unstable wormholes were repaired or replaced by superior versions by the Lord of Rays Weylforges and engineers (associated with the nascent Solar Dominion hyperpolity). 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 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.