"Once, my warriors came in only the white of Chogoris. We were few, and we were proud. But now, I have many sons. Clad in gold, silver, and black. Warriors of the east, south, and west. They strike the blackest fear into the hearts of the Emperor's enemies, put whole swaths of the Galaxy to the torch. They are my father's wrath. They are the undying flame of the Great Crusade. And they come for you now. Fight or flee, it makes no difference to the Horde. They will find you, sooner or later. There is no pit deep enough, no shadow dark enough, for you to escape the coming storm."
― Jaghatai Khan's famous address to Lorgar during the Storm Crusade, M36
Founded as part of the so called "Numroi" Third Founding in during the Nova Terra Interregnum, the Silver Horde were amongst the few Legions created specifically to crush the Nova Terra Serpertists, whose dogged adherence to the Imperial Truth called several other Legions, including the the Space Wolves and Iron Hands, to their banner in open rebellion against the greater Imperium and its recently established Ecclesiarchy. The Legions of the Third Founding were intended to be absolutely gargantuan in size, numbering hundreds of thousands of warriors so that they may simply overwhelm the Sepertists and bring their worlds back under the rule of the glorious God-Emperor.
The Silver Horde was no exception, and rapidly became exemplars of the Numori, teaming rank upon rank of sliver and red clad Legionaries marching from the geneforges of Luna and Mars to utterly vanquish the treasonous unbelievers. Much of the Legion had never known the womb of a human woman, most having been culture in Luna's gene labs by the untold thousands, seeded with the savage legacy of Jahgatai Khan. However, this would only be the beginning, as the Legion still required thousands more than the geneforges could reasonably produce in the allotted time. Every delay in the production of these vast Legions was a mark in the heretic's favor as they were given more time to fortify and fight against the already spread thin Loyalist Legions. And so a world was found, one whose people were worthy of carrying on the legacy of the White Scars. Shataakh Talbar was a hellish world of deserts and volcanic wastelands, its people condemned to harsh and violent lives as nomadic tribes warred for the scant resources available. In spite of the harshness of this world, the tribes were many, and so the gene-wrights took as many viable young men as possible, all but avoiding the extinction of the native peoples.
Soon the Sliver Horde was ready, their Great Khan chosen by Jaghatai himself, who had closely observed the training of the Twenty-first Legion's nascent officer core. Jaghatai had chosen a promising Legionary, abnormally large and fearsome, by the name of Soliotoi Balmadaar, to undergo the enhancements necessary to become a Legion Master. Eager for the blood of the secessionists, the Great Khan led his Legion headfirst into what would become eight-hundred years of bloody, hellish war. And the Silver Horde relished in it.
Having been borne of such rapidly cultured gene-seed and borne from largely experimental flash training processes, the Sliver Horde's inherent genetic flaws quickly became apparent. They were savage, sadistic, and prone to bouts of manic fury in the midst of battle. Their teaming ranks crushed all that dared to stand before them, putting hundreds of worlds to the torch, leaving a string of brutalized and dead worlds in their wake. While other Loyalist Primarchs looked on in horror at what had been wrought of Jaghatai's legacy, the Khagan himself was pleasantly pleased. Though he considered the zeal of his latest and most numerous sons to be extreme, he saw their ruthlessness and savagery as a boon rather than a dangerous flaw. For he knew them to be true Sons of Khan, ferocious on the surface, but born of a deep loyalty and kinship that would see them forever remain loyal unto the Emperor.
Now the Hordes of the Sliver Horde maraud across the stars, relentlessly hunting down and destroying threats to the Imperium from within and without. Their favored foes, the Nova Terra Secessionists, are often subject to brutal raids and forays into their territory, having come to call the XXIst Legion the "Sliver Shroud" in their fear and hatred. The Sliver Horde fights with crushing waves, striking so fast and so savagely as to utterly overwhelm the foe. Sandstorms are kicked up in the charges of their vast bike squadrons, and the very earth trembles under the footfalls of their swarming Legionaries as they charge headlong into battle, heedless of losses in the face of a worthy foe.
"Mundus Cineres is a hellish planet. Not enough moisture for even yearly rainfall, most of the soil is toxic, and whatever breaths is either carnivorous or at the very least not picky about what it puts down its gullet. Still, humans inhabit its scorched surface. I don't know if you can really call them human though, if we're being brutally honest."
Though nominally pure, the Legionaries of the Silver Horde are known for relatively common mutation within the Ossmodula which causes them to grow into hulking warriors, easily a head taller than what is normal for any Legionary. Said Legionaries are also freakishly strong and durable, even by the high standards of the Legio Astartes, capable of grappling with fully grown Ogryns bare handed and unarmored. Though not uncommon, the mutation is rare enough for it to carry special significance within the Legion, who dub these hulking and brutish Legionaries the Songoson, which roughly translates from the Talabar tongue as "Chosen". The Sliver Horde holds that the Songoson are blessed by the spirit of the Khan, and thus are given a portion of his strength and ferocity. The Great Khan himself is often considered the first and greatest of the Songoson, as his physical feats of might have only been rivaled by their gene-father and his brother Primarchs.
The Silver Horde are also known for a general mental degradation due to the various inherent flaws in their rapidly cultured gene-seed. Bluntly, the Legionaries of the Silver Horde are violent savages who instinctually delight in violence and the bedlam of the battlefield, the inate savagery of their genetic heritage combining with their tainted seed to make them every bit as overzealous and blood thirsty as the ancient Thunder Warriors of the Unification Wars. While defects are usually mild enough that a lone Legionary would not typically exhibit them in any significant fashion off the field of war, when in a group setting with their like-minded Battle-Brothers or in the heat of battle, the barbaric urges become exacerbated and eventually overtake an otherwise sane Legionary. When in this frenzied state, the Silver Horde becomes a force of implacable killers, butchering anything that dares to cross their path in a raving state of savage fury. The Songoson are said to suffer doubly from this flaw, dubbed the Storm Rage or the Khagan's Wrath by the Legion itself.
Other than their savagery, it should be noted that the Silver Horde Legionaries are known for their manic, easily excited mannerisms. Often likened unto hunting hounds, the Legionaries of the Silver Horde naturally become anxious before battle, many of them developing minor nervous ticks and impatient mannerisms as their careers carry on into the centuries. However, in the rare times they are off the field of war, the Legionaries of the Silver Horde are known to be gregarious and relaxed by the standards of their fellow Space Marines, surprisingly sociable and easy going for a Legion famed across the Imperium as a living scourge that leaves nought but dead worlds in their wake. For the Sons of Khan are all creatures of extreme passions, quick to anger, and equally quick to calm. The Silver Horde are little different, their moods often changing with the winds, and their fury as sudden and ferocious as any earthquake or thunder storm.
"We are as arrows, loosed in the thousands to rain down upon the foe. May we all strike true!"
―Etsej Khan, commander of the 41st Horde
In spite of their venerable age, the Sliver Horde lacks much in the way of venerable relic weapons and advanced wargear of ages past. This is simply due to the sheer mass of Legionaries the Silver Horde
"Their heads already belong to the Khagan, they just don't know it yet."
―Unknown Outrider during the Vespis Airfield Massacre
Vanguard riders and deep strike squads of great renown, the Legion Outrider Squads are a continuation of the traditional Legion Seeker Squads of the First Great Crusade. Expert hunter-killers and raiders, the Legion Outriders of the Silver Horde typically deploy onto the field of war in squadrons of highly mobile Assault Bikes adorned with the skulls of those who have fallen to their blades before or equipped with Jump Packs that rumble and roar like thunder. Marked with ancient Talbariese death iconography and crimson thunderbolts of vengeance and retribution, the Legion Outriders are savage battlefield assassins who rip out the heart of the enemy's command structure.
They are known to cause lesser foes to flee at the mere sight of them, so fearsome is their visage, and even the mightiest warlord can ill hope to defend himself from such warriors as they strike suddenly and without warning. Legion Outriders often come equipped with their ritual Tolgoig Pattern Axe Rakes, weapons designed for brutal decapitating blows and hooking swipes to keep their quarry from fleeing, and vicious Khuikh Pattern Scalping Knives.
"You think walls can save you!? The very earth quakes at our passing, the skies burn and tumble from their perch at our calling, we are the Khagan's rage and Emperor's fury made flesh and bone! Nothing can save you! NOTHING!"
―The Great Khan's enraged words during the Siege of Byzain Castle during the famous Storm Crusade, M36
Known more widely by his title, "Soliotoi the Immense", the hulking warrior by the name of Soliotoi Balmadaar has been the Legion Master, or Great Khan, of the Silver Horde since its inception during the Nova Terra Interregnum in M34.