Dou Rong, a Han Dynasty official whose family had served for generations in the Hexi region, was appointed General of Boshui when Wang Mang usurped the throne. After Wang Mang's fall, Dou surrendered to Liu Xuan, a distant imperial relative crowned emperor by the Lülin peasant army, and was made Commandant of Zhangye. When Liu Xuan was defeated and hanged by the Chimei rebels, Dou united five commanderies including Jiuquan and Dunhuang, seizing Hexi as self-appointed Grand General commanding all their forces.
In 25 AD, Liu Xiu, a distant imperial relative, rose to power through a peasant rebellion and declared himself emperor in Luoyang. Dou Rong, wanting to pledge allegiance, sent a letter to Luoyang. Liu Xiu, eager to isolate the warlord Wei Xiao who controlled Tianshui, Wudu, and Jincheng, was thrilled by the letter. He issued an edict appointing Dou Rong as Governor of Liangzhou and bestowing 200 jin of gold as imperial gifts. Upon receiving the edict, Dou Rong and his officers believed Liu Xiu could accept them, saying, "He sees clearly from a thousand li away."
Dou Rong, after pledging allegiance to Emperor Liu Xiu, tried to persuade his old ally Wei Xiao to also submit to the Han court. Wei Xiao not only refused but launched an attack on Han forces. Dou Rong then assisted Liu Xiu in retaliating. Defeated repeatedly, Wei Xiao died of grief and rage, and his son Wei Chun eventually surrendered to the Han dynasty.
Dou Rong was later enfeoffed as Marquis of Anfeng by Liu Xiu and appointed Grand Minister of Works.
Later, the idiom "Seeing Clearly for Ten Thousand Li" came to describe having a thorough understanding of distant situations, often used in ancient times as flattery toward rulers.
Source: *Book of the Later Han*, "Biography of Dou Rong"
Meaning of the Idiom: Later, the Chinese idiom "明见万里" came to describe having a thorough understanding of distant situations, often used in ancient times as flattery toward rulers.