The Naruto series is set in an era of peace of prosperity, with wars and conflicts almost non-existent. To attain this peace, however, the shinobi world had undergone several dire events that changed the course of the entire world, with the Warring States Period being one such major event. This was an era of violent conflict that lasted several decades, forcing shinobi factions to fight each other as nations hired mercenary clans to do their bidding.