Cadian Sector - Post-Heresy: Following the Battle of Terra that ended the Horus Heresy with Horus' death and the internment of the Emperor of Mankind in the Golden Throne, the defeated Traitor Legions and their allied forces among the Imperial Army and the Dark Mechanicus fled from Terra. Some of the exhausted Loyalists rallied and gave chase, but most remained on Terra to consolidate their great victory over the Forces of Chaos. Many of the surviving Traitors were put to the sword, but the majority of the Traitor Legions escaped into the great Warp rift known as the Eye of Terror in the Segmentum Obscurus, a region of space where reality and the insanity of Chaos collide as the raw psychic energy of the Immaterium pours into real space-time.Within the Eye of Terror, the Chaos Gods rule over uncounted numbers of planets, all warped to reflect their own dark aspects. It was there that the Traitor Legions found refuge, isolated from the rest of the galaxy by potent Warp Storms. Each of the planets within the Eye is a Daemon World, warped and twisted by the whims of the Ruinous Powers and the powerful Daemon Princes who rule over them in the Dark Gods' name. The Chaos Space Marines regrouped and nurtured their hatred of the Imperium, planning for the day when they would wreak a terrible vengeance on those who had defied them and their foul masters. Within the Eye time flows differently than in realspace. Those same Traitors who fought on Terra 10,000 standard years ago still fight today in the service of Chaos. They fight against each other to prove their supremacy and against the forces of the Imperium when the Warp Storms calm enough to allow them to emerge into Imperial space.The Imperial sectors surrounding the Eye of Terror are heavily militarised to resist these frequent invasions and none more so than Cadia, the Imperial Fortress World that stands at the very mouth of the only stable navigational route leading out of the Eye of Terror, the dreaded Cadian Gate. The planet's strategic location meant that it would prove useful to the Imperium and in the 32nd Millennium Imperial colonists were dispatched to resettle the world, becoming the ancestors of the present-day population of Cadians. Perhaps as a result of the Eye of Terror's proximity, this later population of Cadians also soon developed the unusual violet-coloured eyes that had marked the first human inhabitants of the planet.Cadia stands upon the only known reliable route out of the Eye of Terror and thus is one of the most strategically vital worlds in the entire Imperium of Man. There are other routes out of the Eye, but none are stable like the Cadian Gate and no military force of any true size can venture forth from the Eye without first passing through it. The exact reasons for the existence of this unusual region of stability is unknown, though many Magi of the Adeptus Mechanicus believe it is due to the presence of the famous Cadian Pylons. These mysterious black monoliths, now known to have been created by the Necrons millions of standard years ago to hold back the psychic influence of the Warp that was so feared by their C'tan masters, dot the landscape of Cadia and their origins remained mysterious until the time of the 13th Black Crusade.Cadia itself is a bleak, merciless and wind-blown planet, where only the strongest survive to adulthood and discipline is learned from the moment a babe takes his or her first steps. Cold winds howl across wide, sundered plains where armies train with live ammunition and every day not spent training is believed to be a day wasted. Every Cadian fortress-city, or "Kasr", is a great citadel, with the streets and buildings fashioned with great tactical cunning by the finest military engineers and siege specialists of the Imperial Guard. Every Cadian is taught the skills of the warrior as soon as they can walk and they are much sought after by commanders throughout the galaxy. Cadian military gear is considered top-rate and is used as the standard for all Imperial Guard Regiments. Such a world breeds hardy and determined warriors and the Cadian Regiments of the Imperial Guard have a well-deserved reputation for both honour and fighting spirit. From the earliest age, Cadians are taught to field-strip a weapon with their eyes shut and tactical doctrine is taught before basic literacy. One soldier in every ten is recruited into the Cadian Interior Guard, regardless of ability or achievements, and as a result some of the most able soldiers spend their entire Imperial military service on Cadia and the soldiers of the Cadian Planetary Defence Force are amongst the most skilled fighting men in the Imperium, the equal of many other worlds' Imperial Guard Regiments.