During the Eastern Han Dynasty, a Confucian scholar named Zhang Kai, styled Gongchao, was deeply learned in the classics but refused official posts, choosing instead to teach, with hundreds of students flocking to his lectures.
Zhang Kai's reputation grew so immense that officials constantly visited seeking his guidance, which he found deeply irritating. He retreated to Hongnong Mountain in Henan to live in seclusion, but his devoted students refused to leave him and followed, building their own homes beside his. In no time, this remote mountain valley transformed into a bustling little town, which they named "Gongchao Market" after Zhang Kai's courtesy name.
Soon after, Emperor Shun of Han ascended the throne. Knowing of Zhang Kai's reputation for talent, the young emperor believed his seclusion was due to local officials failing to honor worthy men. He issued an imperial decree, ordering the Governor of Henan to prepare lavish gifts and invite Zhang Kai to serve as an official. Zhang Kai declined, citing poor health, and remained in retirement.
Zhang Kai was not only a master of Confucian classics but also deeply studied Zhuangzi's Daoist teachings; legend has it he could conjure a dense fog covering an area of five li in every direction, so the area around Hongnong's Gongshan Supermarket was often shrouded in mist. Unexpectedly, in the Guanzhong region, a man named Pei You could also create fog, but only within a three-li radius. Pei You used this fog as cover for theft and robbery. Soon, Pei You was arrested for his crimes, and during interrogation, he falsely claimed that he had learned the art of fog-making from Zhang Kai.
As a result, Zhang Kai was implicated and imprisoned for two years. It was eventually determined that Pei You's fog-making skills were not learned from Zhang Kai, and Pei You's theft and robbery had nothing to do with him, so Zhang Kai was finally released and returned home.
Later, Emperor Huan of the Han Dynasty issued an imperial decree summoning Zhang Kai to the capital for an official post. Having endured two years in prison, Zhang Kai had no desire for government service. He firmly declined the imperial appointment and spent his remaining years in the Hongnong Mountains.
Later, the idiom "Lost in Five Li of Fog" came to describe a misty fairyland or to generally refer to dense fog.
Source: *Book of the Later Han*, "Biography of Zhang Kai"
Meaning of the Idiom: Later, the Chinese idiom "五里雾中" came to describe a misty fairyland or to generally refer to dense fog.