"All of creation cares not whether you live or die."
|“||Even now, Earth smolders in ruins, fallen to the Demon Lords, and the Destroyer carves a new kingdom amongst his mighty Chosen.
— The Crowfather, on the Earth
Earth, also known as the Third Kingdom or the Kingdom of Man was one of the Three Kingdoms and home to the Human race. It is the only known realm to explicitly lack an incarnation of the Tree, as its manifestation was burned to cinders by the Charred Council to restrict access to the realm.
The home of the humans. However, originally they were meant to live in Eden, but after the final Nephilim battle humanity was relocated to a different world dubbed Earth. Being targeted once again by the machinations of cosmic players, the scheming Lord of Hell, Lucifer, would take the hysterically vengeful Lilith into his care, who sought restitution for Mankind's part in the Nephilim genocide by four amongst their former number.
Using a soul-charged device known as The Animus, the two schemed to use the collective essence of various celestial and infernal lords as fuel for a mass corruption that would turn denizens of the Third Kingdom violent and ravenous. A ploy discovered too late to have been carried out by Riders War and Strife, the two having carelessly dispatched the needed recipients playing party in the demon kings gambit, thus irrevocably changing the nature of the Kingdom of Man and its denizens.
To that end, the Council would revoke access to the human world; tearing down and incinerating it's incarnation of the Tree of Life after placating Seven Seals, a tithe installed to prevent the unsanctioned interaction with the mortal plane by either the First and/or Second Kingdom's as well as any other individuals who safeguard/serve the universal balance.
In 1722, a rogue Angel by the name of Makhala descended to Marseilles, France, and led a cult of human followers under the influence of Corruption. Her pendants cured their wearers of Corruption but infected those around them. The angel's schemes were ended when Death hunted her down on Earth and killed her.
Earth was in the midst of its modern age when the Apocalypse began prematurely. Humanity, originally protected by treaties between Heaven and Hell so that it could reach its full potential, was unprepared and annihilated in the crossfire between the two sides. The Kingdom of Man was meant to fight on equal footing with the other kingdoms but they had no chance in the early End War. During the initial battle, War descended to Earth and bore witness to the start of mankind's fall. After falling in battle with Straga, his soul was banished to the Abyss, not to return to Earth until the Charred Council sent him back a century later to slay the Destroyer and the conspirators that triggered the early Apocalypse.
By that time, most of the Earth's surface had been reduced to ruin in Hell's victory, reduced to crumbling structures, seas of ash, and demonic growths scarring the blasted landscape. Only a handful of Angels hadn't retreated to the White City and all that remained of humanity were Undead serving the realm's Demon rulers and feral Wicked prowling the skeletons of its once-great civilizations. War went on to do much to shift the balance of power on Earth's surface: freeing Samael and Azrael from the Destroyer's prisons, slaying the Chosen, bringing the truth of the premature End War to light, and finally slaying the Destroyer himself. With the breaking of the Seventh Seal, the remainder of the Four Horsemen have been summoned to Earth.
Darksiders II 
After the Apocalypse but before War's return, Death traveled to Earth twice in his quest to redeem his brother. The first time, he went to retrieve the Rod of Arafel for Archon Lucien, who promised to clear the way to the Ivory Citadel, where the pale rider hoped to find half of Key to the Well of Souls. There he encountered the Hellguard and saved Uriel from the Swarm when he arrives at the Destroyed City. He found that the Destroyer was using pieces of the Rod to summon such Abyssal Creatures to do his bidding. After recovering the Rod, Death departed.
Uriel and Death met again when the latter came to Earth investigating rumors of a surviving human. The rider found the Hunter living in fear of one of Hell's lesser demon lords, Belial, and slew the demon. Upon finding that he had betrayed his own kind over empty threats as well as the fact that Belial had never had power over his soul, the Hunter asked Death to kill him. The Horseman obliged and left Earth.
After the Apocalypse but during War's imprisonment, Fury traveled to Earth at the orders of the Charred Council to hunt down the Seven Deadly Sins that had escaped their prison. Told by the Council and her Watcher companion that her quest would begin In Haven, Fury would encounter Envy shortly after her arrival, subsequently capturing her after defeating the rabid entity in battle with the Talisman of Sin. Shortly after the battle, Fury would travel through Haven and encounter Ulthane, who was protecting the few remaining humans that he had found.
She would travel the world and meet with all manner of interesting hosts, or do battle with the most insidious of beasts. All while finding other still remaining earthlings left alive during the cataclysm at the request of the Blackhammer in exchange for utility upgrades.
As she traveled, Fury also encountered the Lord of the Hollows; whom made his home within the deepest bowls of the razed & violated world. A being who reticently aided the Black Rider in her quest against the Seven Deadly with the power of his Hollow Magic. At the end of her quest where the Council's betrayals were lain bare and the true reason behind the apocalypse came to light. Fury managed to vacate the Earth to an unknown destination, sheltering away the few humans she and the Makers had saved from the prying eyes of all who wished for their annihilation.
- There is an unconfirmed minor detail that would contradict the common knowledge about Earth's inhabitants' total annihilation. In the first Darksiders, one can sometimes hear gunshots when War is in the Crossroads. This hint at humanity's survival at least in part is confirmed with Death meeting with The Hunter. It was shown in the third Darksiders that some time prior to War's return to Earth, there were humans that survived the onslaught of the Apocalypse, with Fury encountering Ulthane, who was sheltering a few of them, alongside several of his fellow Makers. Along her journey to recapture the Seven Deadly Sins, she would encounter humans survivors, typically in somewhat isolated locations.
- Envy in the guise of Fury's Watcher often brought up the fact about how the other factions, the Seven Deadly included, vying for control over the seemingly insignificant Earth. While there's a whole universe outside of it to explore and conquer. Questioning where such a single-minded obsession of one planet in the cosmos that everyone desperately wants yet was given to Mankind.
- Fury in turn responds that the Universal Balance is the sole reasoning behind their coveting the one world. That way the rest of the wider cosmos can expand without impurity by the constant warring between heaven and hell.