The Calamity and Divergence

The battlefields of the catastrophic showdowns of the Calamity were scattered across Riven, but it was Ashus that suffered the full destructive powers of the gods. Divided by the Ashkeeper Peaks, the fields of the Conqueror Valley were once home to several powerful ruling houses, squabbling over their own goals before being drawn into either side of the conflict of the gods, or abstaining for their own reasons. The immensity of power wielded by the Primaris Deities and Betrayer Gods was enough to wound the landscape for eons, and the irresponsible use of arcane knowledge developed by the mortals ensured the ruin of their own legacy. Little record remains of the terrible war, but its effects are still felt today. The sheer magnitude of the energies unleashed in the ensuing battles by gods and mortals alike was enough to fray the boundaries holding back the elemental chaos, spilling unbridled destruction into the world. It completely rearranged the known flow of magical ley energy across Riven. Over half of the once plentiful pantheon of gods was wiped from existence, and from that remainder the gods were fractured and divided to either side of the war. The dark kingdom of Morde-Dranas was reduced to a fractured crater an eight of the size of Riven itself, but the conflict devastated Riven's peoples, razing entire cities and inspiring in many a desire to flee from this plane of existence entirely. So great was the loss of life during the war that historians believe no more than a third of Exandria’s population survived, leaving only one true remaining bastion of civilization: the Dawn City, Naset.
The world entered a long, dark period of regrowth. The Betrayer Gods were banished once more to their realms of deception and hate, but the threat of their return weighed heavily on the world. The Primaris Deities felt that their involvement in mortal conflict was to blame for the cataclysmic damage inflicted on Riven. They knew that while the divine gateways were left open, the prison planes that held the banished Betrayers would remain imperfect and temporary.
Thus, hoping to ensure that such ruin would not befall Riven again, the remaining gods left their children to fend for themselves. The Creators returned to their own realms, dragging both Betrayer and abomination with them and sealing the pathways to the mortal realm behind them with the Divine Gate through Xapham's powers of creation. Only in this way could they prevent their corrupted brethren from physically returning to the material plane. Sadly, for the Primaris Deities, this action also carried with it a self-imposed sentence of exile. The Creators would henceforth never be allowed to visit their creation.
The disappearance of the gods is known by many names: the Second Spark for those who study the arcane, and the Penance for those who seek closeness to their gods. The most common name for this time of warfare and divine separation is the Divergence, and it marked the end of the Age of Arcanum.
Much time has passed since, and the world has been reborn once again. The gods still influence and guide from beyond the Divine Gate, bestowing knowledge and power on their worshipers, but the path of mortals is now their own to make. New cities, kingdoms, and cultures have retaken the world, building over the ashes of the old. New songs fill the air, and the hope of a brighter future drives people day after day, while buried ruins and ancient relics remind all people of a darker time of mistakes that should never be repeated.