It is said that after being mysteriously transported from Terra through the Warp by the Ruinous Powers of Chaos, Khan landed on a planet in the Segmentum Pacificus named by the Imperium, Mundus Planus, or as the native population called it, Chogoris. It is a fertile world with wide, open, green plains and tall, white mountains and blue seas. At the time of the Great Crusade, the Chogoran or Planan people had managed to restore their technological level to one similar to the pike-and-shot level of the late Renaissance on ancient Terra. The dominant empire was a well organized feudal aristocracy which had conquered most of the planet with well equipped and highly disciplined armies, maintaining armored horsemen and tight blocks of pike and arquebus-armed infantry. Their leader was the Palatine, and he won all of his battles with this great army.
To the west of the Palatine's empire was the Empty Quarter, a barren grassland with few resources, and as such it was never invaded by the Palatine's armies. It was home to wandering tribes of vicious horsemen who fought each other for their ancestral lands. The Palatine would sometimes lead forces into the Empty Quarter to capture slaves or merely to hunt the tribesmen for fun. Khan's legacy began here. He was found by Ong Khan, leader of a small tribe called the Talaskars, who saw the young Primarch as a gift from the gods. It is said he had a fire in his eyes, the sign of a great warrior. He was hated by the other tribes because of his ability to see beyond the constant warfare on the steppes to a vision of unity for all the downtrodden peoples of the Empty Quarter.
It is said the most influential moment in Jaghatai's life was the slaying of his adopted father by the rival Kurayed tribe. Khan, even as a young child, was the greatest warrior of the tribe and gathered Talaskar troops to avenge the death of his father. They moved on the Kurayed tribe and razed it to the ground, killing every man, woman and child in a killing frenzy. Khan took the head of the enemy tribe leader and mounted it on his tent. This is what shaped him into a man of fierce honor, loyalty and ruthlessness. From then on, he swore to end the fighting, unite all the people of the steppes and bring an end to their practive of brother fighting brother.
Khan fought hundreds of battles against other tribes and defeated hunting packs sent by the Palatine. Each tribe the Talaskars conquered was absorbed into the Talaskar confederacy and Jaghatai made military service mandatory while splitting tribes up and merging them with others to remove and ameliorate tribal differences and long-standing feuds. His warriors were fiercely loyal and Khan promoted from the ranks based on merit and ability. Ten summers after his arrival on the world, as the tribe moved to their winter settlements, the Primarch was traveling on a mountainside with a group of his followers. A vast avalanche pushed him and his group back down the mountain, killing the normal men. Jaghatai survived, but could not get back up the mountain in time before the tribe moved on. Khan was caught by one of the Palatine's hunting bands lead by the son of that ruler. All that returned of that band was one mutilated rider with the head of the son of Palatine and a note saying that the people of the steppes were no longer his toys.
When the snows cleared, an enraged Palatine gathered a massive army and determined to march west to wipe the tribes from the face of the planet. He had, however, underestimated the power and ability of Khan and brought his highly-disciplined army of heavily armoured warriors and arquebusiers. This proved to be his downfall as they could not catch the lightly armored Talaskar tribesmen. The constant rain of arrows from the tribesmen took their toll on the tight ranks of the Palatine's warriors. Eventually the tribesmen defeated the army of the Palatine, who escaped back to his capital with a select few bodyguards. The rest of the army was slaughtered, almost to the last man. After the battle, the tribal elders gathered and announced that Jaghatai Khan was now Great Khan of the Empty Quarter .
Khan now began the long process of conquering the rest of the planet, which possessed only a single continent. He gave those cities he besieged two choices, to surrender or be wiped out. Most surrendered, but many were destroyed, utterly wiped from the face of the planet. Eventually they came to the Palace of the Palatine, where he demanded the head of the Palatine on a spike. His request was obliged by the capital city's population, which turned on its own ruler to save their own lives from the fierce tribesmen. Jaghatai Khan adorned his tent with his greatest conquest's head, just as he had with his first enemy two decades before.
In only twenty years he had conquered the largest empire in his world's history. He now had the problems of ruling that empire, not something he had originally expected. His nomadic people had no wish to rule these new, settled lands, only to carry on living in their old ways. The Talaskar people dispersed back to a tribal existence and Khan ruled over them all with his generals by his side.
Six months later, the Emperor of Mankind arrived on the world as part of the Great Crusade and Khan knew at once that this man could fulfill his dream, to unite all of the stars above them and all of humanity in one mighty empire. In front of all of his generals, he dropped to one knee and pledged his service to the Emperor. He was given command of the V Legion of the Space Marines, the White Scars, who had been created from his own genetic material. Khan eventually grew close to Lion El'Jonson, the Primarch of the Dark Angels, and his Marines would work in conjunction with the Dark Angels on many occasions.
The Horus Heresy
The Legion's legend grew with the events of the Horus Heresy, when the White Scars fought on hundreds of worlds for over 7 standard years against the Traitor Legions and the other Forces of Chaos. Unlike many of the other Primarchs, Jaghatai never even considered betraying the Emperor for the service of the Ruinous Powers. Such a course would have been dishonourable in the extreme since the Emperor had done no wrong to his sons and also because Jaghatai so deeply believed in the Emperor's goal of reunifying the entire human race under a single ruler so that it might claim final dominance over the Milky Way Galaxy. The White Scars Legion had already been engaged for several standard years in a punishing campaign against the Orks of the Chondax System when the news of Horus' betrayal of the Imperium and the actions of the Traitor Legions at Istvaan III and the Drop Site Massacre of Istvaan V reached the White Scars' Expeditionary Fleet. They were urged in an astropathic message by the Imperial Fists Legion's Primarch Rogal Dorn to return to Terra to help defend the homeworld of humanity from the Traitors as soon as possible. Jaghatai was next contacted by the Space Wolves' Leman Russ who had just returned from the Burning of Prospero and the assault against the Space Wolves old rivals the Thousand Sons Legion and offered to join his Space Wolves with the White Scars so that they could face the Forces of Chaos in a united front. But Horus had anticipated this move by the two close brother Primarchs and the Warmaster deployed the Alpha Legion to launch a massive assault on Russ' outnumbered Space Wolves. The Alpha Legion and its twin Primarchs, Alpharius Omegon, had long harboured deep grudges against the Space Wolves and Russ in particular for his criticism of their reliance upon trickery, manipulation and subterfuge to win battles rather than engaging in what the Space Wolves Primarch saw as honourable, open combat. The Alpha Legion relished the chance to prove their superiority against the arrogant Wolves of Fenris by delaying them long enough to keep them from contributing to the defence of Terra.
Although he despised leaving the Space Wolves to face the Alpha Legion Traitor Marines on their own, Jagathai Khan felt it was more important to honour Dorn's urgent request to retreat to Terra immediately rather than first engaging in a costly (and diversionary) battle against the Alpha Legion.
It is known that much of the White Scars Legion, including its Primarch, was present to defend the siege of the Imperial Palace during the climatic Battle of Terra alongside the Blood Angels and Imperial Fists Legions. It was said that Jaghatai and his men fought many of the Chaos Space Marines that tried to retreat to Terra's spaceports and flee, following the death of the Warmaster Horus at the hands of the Emperor aboard his Battle Barge Vengeful Spirit in orbit of Mankind's homeworld. The White Scars launched several highly-successful hit-and-run assaults against the Traitor forces and together with remnants of the Imperial Army's 1st Terran Tank Division and several infantry regiments they successfully harassed the enemy supply lines as the Chaotic armies fled to the Lions Gate Spaceport to get off-world and flee Imperial vengeance. It is said that Jaghatai led these assaults from the top of a Razorback, a tale that still elicits awe from those audiences who hear it ten millennia later.
Seven years after the end of the Horus Heresy during the period called the Reformation when the Imperium was largely guided by the Ultramarines Primarch Roboute Guilliman, the White Scars adopted Guilliman's Codex Astartes and the Legion allowed itself to be grudgingly divided into several different Successor Chapters. In order to contain the outlaws, renegades and aliens that dwelled within the Maelstrom and had taken advantage of the disruptions caused by the Heresy to run amok in the Ultima Segmentum, Roboute Guilliman ordered the surrounding star systems to be reinforced. The White Scars were tasked with the main responsibility of securing the area from their homeworld. According to the writings of the Great Khan of Quan Zhou, the White Scars learned upon their return to Mundus Planus following the end of the Heresy that their homeworld and its people had been the target of numerous raids by the Dark Eldar to seize thousands of Planans as slaves. Jaghatai swore many oaths against the Dark Eldar because of this crime and fought them in many battles until peace had largely been restored among the Imperial worlds that were adjacent to the Maelstrom.
Jaghatai fought alongside his sons of the White Scars for another 70 standard years following the end of the Horus Heresy, eventually disappearing into a region of space known as the Maelstrom, a large Warp rift in the Ultima Segmentum that is a somewhat smaller counterpart of the Eye of Terror. Jaghatai is believed to have been in pursuit of the Dark Eldar who had savaged Mundus Planus following the Battle of Corusil V with his 1st Brotherhood when he went through a Warp Gate into the Dark Eldar portion of the Webway, ultimately vanishing forever. Jaghatai had been in pursuit of a mighty Dark Eldar lord, likely the Archon of the Kabal that had attacked Corusil V and perhaps even Mundus Planus itself. Jaghatai Khan has not been seen since, though the White Scars believe he is still alive somewhere within the Webway and will one day return to the Chapter in a time of great need. As a result of their Primarch's disappearance, the White Scars hold a particularly savage grudge against the Dark Eldar and will gladly seek out any opportunity to make war upon those savage and terrifying xenos.
- Index Astartes I, "Lightning Attack: The White Scars"
- The Horus Heresy, Collected Visions
- A Thousand Sons (Novel) by Graham McNeill