After having proved to be key in sealing Calamity Ganon 10,000 years ago, ancient Sheikah technology was at first praised as the power of the gods. However, the people of Hyrule began to fear their technology as a threat to the kingdom. As a result, the Sheikah became outcasts and lived in exile. Although most Sheikah chose to cast off their technology and live simple lives, others fostered hatred towards the kingdom of Hyrule for shunning the Sheikah despite all they had done for it, leading them to swear allegiance to Ganon. This resulted in the creation of the Yiga Clan, who dedicate themselves to eliminating all who stand against Ganon.
          The Yiga adopted the upside-down sigil of the Sheikah, representing their resentment of the clan, as their own symbol and setup their base of operations within Karusa Valley in the Gerudo Desert. From there, the Yiga Clan would attack and strike down anyone who even thought negatively of them or Calamity Ganon, specifically targeting members of the Sheikah, the Hyrulean Army, and the Royal Family. The clan gained a notorious reputation for cruelty, with some even regarding the organization as "pure evil", and used underhanded tactics to gain information, recruit, or simply murder in cold blood. Others however saw the organization as lost souls who were being manipulated by Calamity Ganon, who simply saw them as useful pawns to further his own goals of destroying Hyrule and the world beyond.
          The Yiga Clan were active 100 years ago shortly before the events of the Great Calamity. At one point, the Yiga Clan attempted to assassinate Princess Zelda before she could awaken her sealing powers which were a great threat to Calamity Ganon's return. However Zelda's appointed knight, the Hylian Champion Link heroically defended her from the Yiga Clan blades.
          At the same time, the Yiga were plotting to resurrect Ganon and were making plans to steal the Thunder Helm from Gerudo Town. The organization may have therefore played a key role in Ganon's return to Hyrule. While Ganon continued to build up his power, more and more monsters emerged throughout the land, odd disasters took place, and the Yiga escalated their own activities, targeting Princess Zelda and the Champions in order to prevent their roles in fighting their master from coming to fruition.
          Calamity Ganon managed to turn the tables on the Champions and their allies when he corrupted the four Divine Beasts with his blights which killed their champion pilots. Link was ultimately injured defending Zelda from Guardians at Fort Hateno, causing Zelda's powers to fully awaken. Even with Link incapacitated, the Yiga failed to kill Zelda who used her power to seal herself and Calamity Ganon in Hyrule Castle. The Yiga Clan's activities during the Age of Burning Fields is unknown but it is believed that they continued to hunt down the enemies of Ganon such as surviving Knights of Hyrule and Hyrulean Soldiers. However they were unable to eliminate Zelda and Link's Sheikah allies Robbie, Purah, and Impa who split up in order to survive long enough to aid Link. Impa remained in Kakariko Village to lead the Sheikah still loyal to the Royal Family and Sheikah who came to reject the evil ways of the Yiga Clan, while Purah and Robbie left to establish the Hateno Ancient Tech Lab and Akkala Ancient Tech Lab respectively with all three of them avoiding being killed by the Yiga for 100 years.
           To this day, the Yiga remain a dangerous force throughout Hyrule. They roam the countryside, attacking unwary travelers and agents of good alike. When Link was resurrected they began a campaign to annihilate him once and for all, employing all of their stealth and disguise tactics in this endeavor. Throughout the Hero's journey, he was consistently plagued by Yiga assassins who disguised themselves as travelers or even as hapless victims of monster attacks.