In the fourth year of the Jianwu era of the Han Dynasty, Emperor Guangwu appointed Geng Guo as a Gentleman Attendant at the Yellow Gate, an imperial advisor role.
Geng Guo, a man of vast knowledge and sharp wit, served Emperor Guangwu of Han as an imperial advisor, always ready with clever strategies that earned him deep trust. Promoted first to Colonel of the Archers (a high-ranking military post) and then to Commandant of the Imperial Equerries (a close attendant role), he was a rising star. One day, the Emperor asked him, "What do you think of the northern frontier?" Geng Guo replied, "The Xiongnu are restless, but if we befriend the Wuhuan and Xianbei, we can secure the border without a single battle." The Emperor nodded, "Your plan is sound—I'll make you the one to carry it out." This advice led to a lasting peace, proving Geng Guo's wisdom was as sharp as his arrows. Today, this story reminds us that true strategy wins without bloodshed.
In 36 AD, during the Han Dynasty, Geng Guo's father, the Marquis of Yumi, Geng Kuang, passed away. According to state law, Geng Guo was entitled to inherit his father's title. However, Geng Guo firmly petitioned the throne, arguing that his father had favored his younger brother, Geng Ba, and insisted on yielding the marquisate to him. Emperor Guangwu was deeply impressed by this selfless act and summoned Geng Guo, appointing him as a high-ranking imperial guard commander.
One day, Emperor Guangwu of the Han Dynasty addressed his court, mentioning that the Xiongnu chanyu Huhanye had sincerely petitioned to become a vassal of the Han and pledged to help defend against the northern Wuhuan and Xianbei tribes. As soon as the emperor finished speaking, the ministers erupted in disagreement, arguing that the Han, exhausted from years of war and just beginning to recover, was too weak to trust the barbarian Xiongnu. Only General Geng Gu disagreed, stepping forward to say, "Your Majesty, this is a rare opportunity. Accepting their submission will strengthen our borders and show the world the Han's magnanimity."
“Back in the day, during the second year of Emperor Xuan’s Ganlu reign, Chanyu Huhanye came to court to pledge allegiance. The late emperor sent two thousand elite cavalry to welcome him from afar—an honor surpassing even that of feudal princes. Now that the Xiongnu have come to submit, I believe we should follow the late emperor’s precedent in receiving them. At the same time, we should order them to guard against the Xianbei to the east, repel the Wuhuan to the north, and lead the surrounding tribes to protect our border commanderies. This way, our frontier will never again face the panic of a sudden alarm where opening the gates comes too late. This is a strategy for eternal peace!”
The assembled officials fell silent.
Emperor Guangwu of the Eastern Han Dynasty accepted General Geng Guo's advice and agreed to the Xiongnu Chanyu's request for submission.
From then on, the Wuhuan and Xianbei tribes guarded the border and kept to themselves, bringing relative peace to the Central Plains.
Later, the idiom "Yan Kai Zhi Jing" came to be used as a metaphor for alarms of enemy raids and invasions.
Source: *Book of the Later Han*, Chapter "Biography of Geng Guo"
Meaning of the Idiom: Later, the Chinese idiom "晏开之警" came to describe a metaphor for alarms of enemy raids and invasions.