Instagram photo by saledron_ravencrestThe genocide of the draenei was a major conflict which occurred on the planet of Draenor between the world's draenei inhabitants and the newly-created Orcish Horde.
Having been persuaded and corrupted by agents of the demonic Burning Legion, the various orc clans of the planet Draenor united to form a new force known as the Horde. Now, they were directed to utterly wipe out the planet's other most powerful race, the draenei, who had being fleeing the Legion's wrath for millennia by moving to new worlds when they had been discovered.
With relatively little effort due to the vastly larger numbers of the united clans and newly-gained powers, the Horde succeeded in pushing the draenei back from many of their major settlements and strongholds. Although confused by the orcs' sudden aggression and drive to make war on them, the draenei nonetheless did their best to preserve their civilization. Ultimately, however, they were overwhelmed and forced back to their last bastion and capital in the form of Shattrath City. Realising that there existed no hope of overcoming their foes, the draenei leader Velen reluctantly led a group of refugees into hiding away from the battle. Utilizing their new demonic abilities, the orcs breached and sacked the city.
In the period following the Horde's victory over the draenei, and believing that no more of their adversaries remained, the orcs turned their attention to a new conquest, in the form of the distant planet of Azeroth. (Official art from World of Warcraft: Chronicle Volume 2)