Pearlescent Expanse

The Pearlescent Expanse is a region of space near the edge of the Milky Way galaxy.

Early History
The Pearlescent Expanse originated from human settlers from Earth, which formed the Coalition, sworn by the Seven Representatives on their blades. The original Representatives were each from the Dodonan Tribunal, Terrenon Dynasty, Nadezhdan Exiles, Peacock Conglomerate, Jovian Flotilla, Banner Post, and Lunar Pact (later known as the Syzygy Combine).

One of the major early steps of the Coalition was to negotiate the decommissioning and surrender of the Voice of Glass—a superweapon known to have been capable of at least planet-wide devastation—from the Nadezhdans.

Not long after its founding, the Seven Representatives agreed to sequester the Earth, leaving it and its inhabitants abandoned as they left to journey into the wider galaxy.

The Discovery of the Singing Deep
As the Coalition ventured into space, the Singing Deep—a harmonic abyss through which humanity could travel quickly—was discovered, and the first melody-gate was constructed: Gate Zero. Through it, the ship Firstborn entered the Singing Deep, the first members of the coalition to do so.

Deep travel brought danger and losses: a Coalition songship known as Star Opal was lost in one of the many subsequent journeys, never to return.

As the Coalition's journey continued, the planet Fugue was encountered several times in several different locations. It was discovered that, because it's surrounded by the Singing Deep, it's able to exist in several places (superpositions) at once.

Towards the end of this age, the Nadezhdan Exiles were led to a new, frigid homeworld by Tir Brass, which was named Nadezhda.

The Age of Silver Expansion
Advances in technologies such as melody-gates and songships enabled Coalition colonies to rapidly expand into new reaches of real space, many never looking back to the local cluster from whence they came. This new frontier became known as the Silver Frontier.

As a rejection of the Coalition, the Seventh Sword—one of seven swords that symbolised the Coalition at its founding—was smelted down as a symbolic gesture in the founding of the Church of the People's Spirit. This new religion would focus on the power in community action, and their beliefs sowed the foundation of what would eventually become the Universal Choir.

A consequence of this rapid and wide expansion was that information began to take much longer to reach its destination, causing—among other issues—confusion when a new Representative stepped forth after the mysterious death of their predecessor.

The Banner Post began to dedicate themselves to safe and efficient delivery of information, but their couriers were subjected to attacks motivated by resource scarcity and distrust of the distant Coalition leadership. The Banner Post, however, showed themselves more than capable of self-defence, earning them grudging respect among colonists.

Among those travelling to the colonies, the heart-song of the Deep was heard—and out of the immediate line of sight of the Coalition, the 7th Mantra Foundation was formed, set to focus on cutting edge Singing Deep research.

However, the relative freedom of this uncharted space wouldn't last forever. Eventually, the governing body of the Coalition arrived and titled this region of space The Pearlescent Expanse. In opposition to this incursion, a handful of Banner Post couriers formed an underground colonial rebellion movement.

The Era of the Peoples' Crown
To re-unify the Coalition, the Peoples' Crown was formed, as a way of forcing cooperation among increasingly disparate factions. A fake figurehead leader was installed as a scapegoat, and a civil cold war broke out.

On Aureate (the designated capital of the Expanse), the Havzhiva Academy was founded—a clearinghouse for all the knowledge of the Coalition.

Elsewhere, on Fugue, a creature from the Singing Deep was discovered—a floating, orb-like organism called a Note. It's also discovered that three such creatures form another type of creature called a Chord.

In this period, a new faction emerged across Coalition space: The Thousand Moons' Creed, which claimed a deep history and an ancient pact between themselves and the Lunar Pact.

A sect of the Creed, called the Gibbous Tide, was also formed, with the goal of hunting Chords across Coalition space under the command of Representative Procellarum. However, the Gibbous Tide was dealt a major blow in an attempt to defend a spaceport from attacking Chords, and have not been heard of since.

Nadezhda was razed from orbit by a Terrenon Dynasty war fleet, destroying all life on the surface of the planet and heavily damaging its atmosphere—but life continued underground. This sparked a revolt led by Tir Cobalt, where a Coalition vessel hosting four of the Representatives was destroyed in orbit over Aureate.

The Choral Era
As research into the Singing Deep continued, 7th Mantra scientists determined the melody of the song of the Deep, learning how to harmonise with it. The 7th Representative and her people joined the Universal Choir.

Following this, the Dodonan Tribunal cracked down on religion, stating that science should not take the kind of unfounded risks taken by the 7th Mantra. The Thousand Moons' Creed was one of many religious sects to be forced underground in Dodonan territory.

The 7th Mantra, meanwhile, was able to manipulate the Singing Deep such that water and atmosphere could be transported back to Nadezhda on a planetary scale, along with humanitarian aid and Choral missionaries.

Eventually, this terraforming technology was co-opted by the Peacock Conglomerate—first by providing funding in exchange for its use, later by forcing its surrender by force. The Conglomerate began to use this technology instead as a superweapon capable of stripping worlds bare.

Recent History
Following ever-rising tensions, the Coalition is dissolved. The Six Representatives split the Peoples' Crown in an uneven fashion.

As the Expanse split, the remnants of the Voice of Glass went missing under mysterious circumstances.

Meanwhile, the Terrenon Dynasty bombed the Havzhiva Academy, lamenting it as a tool of Dodonan hegemony full of unproductive discourse that prohibited proper governance. Scholars-Errant of Havzhiva became a prized commodity across factions, passing down fragmented lore—gone with the bombing of the academy—through generations.

The Universal Choir, excluded from dissolution talks, took matters of self-defence into their own hands. The Choir ordained a number of ace pilots known as Voices to fight as Psalms in unity with Chords, to protect the Choir's people and interests across the Expanse.

On Aureate, the cold war between its Terrenon and Dodonan occupants after the destruction of the Academy, eventually broke out into a full-on armed conflict. In the middle of this conflict, a new revolution began to rise up in a community known as Vedro, built on abandoned desalination rigs in the Mirror Sea.