The rogue planet known as Valleybridge, located roughly at the barycenter of the Sealed Kingdoms region, serves as a sort of diplomatic crossroads for the various sentient species found therein. Far from the capital of any major civilization - or any stellar body whatsoever - Valleybridge is neutral ground where important matters that affect the region as a whole can be discussed. The famous Valleybridge Accords, banning the use of relativistic weapons on inhabitable worlds among other provisions, was penned, signed, and remains upheld by a generational cadre of diplomats stationed - from womb to tomb - on the icy little world of Valleybridge.
Valleybridge is a roughly Terra-sized world able to sustain its own (extremely chilly) atmosphere of hydrogen vapor and sublimating water ice 'snow.' The two rocky moons of the planet are considered nothing special, and are generally used as remote waystations, platforms for 'dirty' industries, and real estate for communications and reconnaisance facilities.
At some point millions of years in the past, when the planet was still orbiting its parent star, Valleybridge had a vibrant (if primitive) ecosystem composed primarily of water-dwelling microorganisms and small clusters of multicellular plants. After it was flung free by gravitational perturbations of unknown provenance, however, the planet quickly froze, and, over time, much the planet's shallow ocean surface has since sublimated, leaving vast crater-strewn deserts of silvery tan soil in their wake. Nevertheless, Vbyifabid scientists descended from the first explorers to discover the world have managed to thaw some of these organisms, viable despite the transit of eons, and put them to use in the closed ecological life support systems which keep the sealed dome-cities on Valleybridge habitable. These organisms were initially prone to destruction by invasive species of foreign microorganisms contaminating the CELSS tubes, with new die-offs starting with each new wave of colonists and their idiosyncratic pathogens, but the forced evolutionary pressure brought on by these events have rendered these heretofore buried species more resilient than possibly any known throughout the Sealed Kingdoms region. As such, the native flora is now, itself, considered invasive should it happen to hitch a ride aboard the rare outbound spacecraft.
While there is no sunlight to speak of - only the dull red and blue tones of the nebula - to warm the planet, Valleybridge remains geologically active. As with terrestrial worlds like Evermorn, a combination of nuclear decay and intense pressure keeps the core of Valleybridge molten hot, and pockets of magma and steam occasionally breach the planet's crust in the form of geysers, hot springs, and volcanoes. Aside from the hydrogenated atmosphere being tapped for fusion fuel, these geothermal vents are the most common source of heat and electrical power on the otherwise barren and remote world.
The extreme chill of the planet has caused it to accumulate more hydrogen isotopes, among other gases, from the nebulous medium through which it floats, making hydrogen bottling a semi-renewable industry. It is currently believed that, without the intervention of colonists (see Tourism) from all corners of the Sealed Kingdoms, the planet would eventually accumulate enough gas to become a gas giant and, eventually, perhaps even a star in its own right. Colony structures on Valleybridge are either domes beneath the stars or, more commonly, hollows beneath the crust near warm geothermal pockets. In these environments, local water and frozen breathing gasses, such as oxygen, can simply be allowed to thaw for use. The planet retains large deposits of valuable minerals, as the old ecology hadn't really gotten around to tapping them for metabolism yet. Even so, careful efforts are made to conserve any resources taken from the planet, as, besides hydrogen, they must all be made to last for millenia or more with only extremely rare resupply. It is traditional for any diplomatic crew sent to the planet to bring an offering of an uncommon element essential to their physiology, such as sulphur, nitrogen, or phosphorus for human-adjacent speces, as a gift to their new 'neighborhood.'
Far-reaching vby automated drones spotted Valleybridge around five millenia before the end of the Mythic Age, but it would be another two millenia before they set foot upon it. In those days, a rogue planet wasn't considerd very interesting in terms of resources or as a potential colonization site, but it might make an interesting location for a covert forward operating base. The Twelveminds, the VibNet-enhanced collective 'consciousness' of the Vbyifabid Family-Flock, recognized in dominant arcopel hegemony the signs of an eventual species-wide collapse, though it could not predict the cause or exact day. As such, the Family-Flock established a minimal presence on Valleybridge as a hedge against total extinction should this collapse prove violent. Vast domes and sealed underground chambers were created to house a fully self-sufficient population of the four vbyifabid subspecies, who went with the knowledge that they had dedicated their own lives and those of all subsequent civilizations to watching and, perhaps, repopulating sentience into the region in the aftermath. Luckily, the arcopel largely disappeared from the galactic stage as a unified civilization all of a sudden, without the usual death throes of a collapsing hegemon. In a post-arcopel Sealed Kingdoms, without the restraint imposed by a technologically-advanced elder civilization, the chitiquish and others started becoming lax on their commitment to avoiding the destruction of valuable habitable planets through 'R-Bombs' or other means. As such, the vbyifabid and their emoxi allies began to transition Valleybridge from a purely military installation into one for use in general foreign relations. Luckily for them, the chitiquish, ashquilish, gant, and even the TKT proved receptive to this idea, many recognizing the potential of a mutually-assured destruction scenario. This was the earliest development for the Valleybridge Consensus, a diplomatic and peacekeeping council dedicated to the regulation of any technology which could cause artificial mass extinction events in the Sealed Kingdom region. Wurth Harkin's use of cobalt-salted R-bombs against the chitiquish colony which had enslaved his own Evermornan people crystallized the necessity of the Valleybridge Accords in the minds of this body, and, with Evermorn's subsequent adoption of the Accords, brought the Consensus' membership to its current species count.
The barycenter of the Sealed Kingdoms region lies roughly at an equidistant point between the farthest known spacefaring civilizations, but that still doesn't make it close to home for any individual species. For example, an envoy vessel from the Cobalt Protectorate must be either a sleeper ship, as, even at the top Cobalt cruising speed of around one-third the speed of light, a journey to Valleybridge takes around 150 years. Still, this has proven to be something of a boon over the long term, as this tentatively one-way journey - even for the most long-lived of species - indicates the resolve of the traveler to make sure that a semblance of interstellar peace is maintained. It is fo this reason that Protectorate envoys consisting only of transmitted Human-Like Artificial Intelligence are not accepted alone into the halls of the Valleybridge Consensus: every signatory to the Accords must show that they have 'skin in the game' by 'sacrificing' the whole lifetimes of their conspecifics to the 'greatest project' of the age. Occasionally, samples of alien life in seed and embryo form are shipped to Valleybridge for analysis and conservation. Later, should a violation of the Accords be detected, the planet affected can be restored to its habitable state through terraforming processses. This function of Valleybridge has, thankfully, not had to be used since before even the fall of the arcopel civilization or the arrival of humanity in the region. With any luck, this state of affairs will continue long into the future as a result of diplomatic efforts conducted on Valleybridge in the current day.