The Krogan Purge was an event in Krogan history that changed the species history and evolutionary trail forever. Ordered by Urdnot Legacy after the creation of his vast pure-krogan army, the event gave him a chance to bring about a new start for the Krogan. The Purge began in 2240 after Legacy's army of pure-krogan reached an impressive size within a small window of time. Legacy's felt that the original krogan were genetically obsolete creatures who had grown weaker with every generation. To counter this, he began sending out secret brigades of pure-krogan out into the world, attacking Krogan camps across Tuchanka. He then began unleashing these death squads into Urdnot City, the capital of the Tuchanka State Union and largest concentration of the Krogan population, assassinating entire families in the dead of night. This silent genocide went on for weeks before anyone realized that the government was behind the disappearances of millions of krogan. Many of the original Krogan resisted which resulted in a guerrilla war. This lasted for only a few months as nearly all the Krogan that resisted were eventually murdered. The survivors were forced to flee from the Krogan DMZ before being hunted down by Legacy's forces.