Lexicanum is a great resource, and I highly recommend using it, especially if you're not sure on a term used that seems universe-specific. Bear in mind, of course, that it may reveal information your character may not know, but I trust all of you to handle that well.
thumb|right|400px|Map of the Expanse
==The Expanse==
The Koronus Expanse is the name given by Imperial authorities to a dangerous unexplored region of the Halo Stars beyond the Calixis Sector.
==Overview==
The Expanse is accessed through the Koronus Passage, a treacherous but navigable route through the great warp storms that bar the passage to the Halo Stars beyond the way station of Port Wander.
As is true of the Calixis Sector itself, the Expanse was untouched by the God-Emperor's Crusade many millennia ago and so it is a realm of fearsome xenos, treasures beyond imagining, heathen worlds of men, and the echoes of the ancient doom.
==Current state==
The Koronus Expanse in the 41st Millennium is a scattered, partly explored region containing a few young colonies and vast natural wealth still barely explored.
Rogue Traders vie with one another for known resources, heedless of lives lost in the pursuit of riches, while a tentative attempt at Imperial colonization follows in their wake.
Drawn by the flow of wealth, pirates and servants of Dark Gods have also slipped into the Expanse, eager to cast destruction upon the works of the God-Emperor's faithful, living by what they wrest from dead hands, while the Expanse itself holds many secrets and native inhabitants no less dangerous. Beyond these human conflicts lie truly dark and dangerous voids, rife with rumoured terrors, undiscovered stars, and worlds of man who have never known the God-Emperor. There are no defined warp-routes, no safe ways through the swirling empyrean. These regions hold the fearsome Ork, the treacherous Eldar, and strange ruins that lie beneath the light of dying stars.
==Rogue Traders and their involment==
For centuries, Rogue Traders have braved great evils and the treacherous warp to venture into the Koronus Expanse, but their efforts have barely begun to uncover its secrets.Footholds have been built close to the few semi-stable warp routes into the area.
Here, resources-rich worlds are exploited, xenos ruins, trade envoys meet with heathen lords, and colonies are attempted upon sheltered worlds.This effort has been enough to shower wealth and fame upon the fortunate and make corpses of the rest.The gateway to the Expanse is littered with broken vessels and tales of the vanished.
==Warp Routes==
The warp space of the Koronus Expanse is treacherous and unknown in the main, and partially explored regions of the Expanse are islands of Imperial activity admist a vastness of danger and myster.Navigating is a far cry from traversing the established warp routes of the Calixis Sector.
Most of the Koronus Expanse is known to the Imperium only through legend, revelation, and hearsay. The Rogue Trader who ventures into this unknown risks his very soul upon the talent of his Navigator, and on quality of what little information he has gleaned from those gone before.
==Unexplored regions==
Beyond the partly explored regions of the Koronus Expanse, past deeps beset by pirates and dread xenos, lie many worlds and strange phenomena which exists as the stuff of dark legend.Some of these uncharted stars were visited by a single Rogue Trader whose tales are doubted and dismissed by rivals as outright lies, while others are known only from dubious and apocryphal sources such as Thulean data-vaults recovered from Dolorium's voids in 741.M41, or the infamous prophetic visions of the Seven Witches of Footfall.
Other fragments of contradictory lore relating to these dark zones are culled from even more untrustworthy sources, such as the muted astropathic whispers overheard on the warp's twisted eddies, the falsehoods of the deceitful Eldar, or the ancient myths of heathen worlds given over to darkness for millennia uncounted.
Such areas are only labeled only as "Here be monsters" on ancient charts, where only the foolhardy of insane would venture to seek their destiny.
==Sources==
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Category:Halo Zone
Category:The Galaxy
de: Koronus Expanse
fr: Etendues de Koronus
Below, I've posted the introductory passage I wrote yet again, mostly so I can tag it to create pages for everything.
The Koronus Expanse, an area of the galaxy both lauded and vilified for the relative weakness of Imperial law, faces a new crisis threatening to see the sector burn.
Twelve years past, in the year 436.M41, a surge of warp storms in and around the Expanse all but eliminated contact between systems inside the Expanse, and the Expanse to other areas of the galaxy. Though the initial outburst was incredibly violent, the storms inside subsided rather quickly; the sector itself is still, however, cut off from outer Imperial space. The Tau Protector-class cruiser Io’Phi’Ko’s captain, captured outside Port Wander, was interrogated; shortly before his death, he told officials that Imperials outside now feared to enter the Expanse, and spoke of Chaos being mentioned in many intercepted reports. This was, and still is, the only known vessel to have entered the Expanse since the storms began.
These reports of increased Chaos activity would have raised more concern, but the Expanse had been dealing with increased cult and Traitor Marine activity already. The Rifts of Hecaton, long a place of dark myths and suspicion, seem to be the source of the Warp breach. This led to the eventual systemic quarantine, closing off the Cinerus Maleficum and each sector to the west thereof.
One figure rose to challenge this: Arch-Cardinal Dagmar Roft. The head of the Imperial cult within the Expanse, Roft publicly admonished the Administratum for abandoning subjects and citizens, leaving them as sacrificial lambs for Chaos to consume. Various officials in the Expanse expressed support for Roft, while others tried to brand him a traitor. In 442.M41, Port Wander was officially granted to the Arch-Cardinal; all officers aboard the void station supported the decision. Roft and the close friends (and big players) he had assembled have since then used Port Wander as their stronghold and base of operations. In 437.M41, Port Wander began a process of fortifying and expansion; this was completed in 444.M41.
For all of the Arch-Cardinal’s supporters, there exists an equal amount of opponents. Anchored and entrenched on Damaris, a rare jewel of prosperity and civilization in the Expanse. A benevolent junta under the leadership of Lord Militant Commander Zaccariah Antasa and Lord Admiral Jaxon Orpheus has made its home on Damaris. Rogue Trader Bastille the Seventh has taken on the role of their face, and has taken to travelling the Expanse, garnering support for the “real” Imperial authorities in the Expanse; it remains to be seen which will prevail.
From the West, in the Sequester, the sector burns and its people bleed. The Warlord Mel’kar’rahh the Blind leads a unified Chaos band that has steamrolled through the region. The heretics have taken and fortified Rune, Illisk, and Melbethe; Seven Dooms and Marwolv are systems under siege; and reports are coming of the first Chaos-Ork clashes around the [[Undred-Undred Teef] collective. Some within the Expanse are willing to let these areas go; they were riddled with Chaos before, and of little value to begin. Others counter that, while of little value, the footholds gained are only allowing the forces of Chaos to gain more and more strength.
Amidst these discussions, in 442.M41, Antasa and Orpheus compared the Arch-Cardinal to the High Lorde Goge Vandire, who sparked the Age of Apostasy throughout the galaxy in the 36th millennium. Denouncing Roft for appropriating Administratum authority to the Ecclesiarchy, the Damaris forces have branded him a traitor, and accuse him of being behind the original warp storms; some even claim he himself is Mel’kar’rahh.
The Expanse was renowned for its distance from the oppressive Imperium; it is now completely cut off from that law, but also its protection. In these turbulent times, legends are forged and names are made that will, one day, echo throughout the galaxy. The Koronus Expanse has never been riper for the taking- and only the most ambitious, crafty, and powerful player will be left to claim it in the end.