During the Western Han Dynasty, Chancellor Yang Chang was the son-in-law of the famed historian Sima Qian. His son, Yang Yun, was exceptionally bright and well-connected from a young age. Entering officialdom, Yang Yun first served as a palace attendant and cavalry officer, handling court affairs with meticulous care. Impressed by his thoroughness, the emperor promoted him to Left Assistant, overseeing all memorials submitted by officials.
In 66 BCE, Grand Marshal Huo Yu, Marquis Guanyang Huo Yun, and Marquis Leping Huo Shan, having lost the trust of Emperor Xuan of Han, plotted rebellion. Yang Yun uncovered their scheme and reported it through imperial advisor Jin An to the throne. The Huo clan's uprising was nipped in the bud, and Yang Yun was ennobled as Marquis Pingtong for his service.
During the Han Dynasty, many junior officials in the palace were wealthy and routinely bribed their supervisors to secure plum positions, creating a pervasive culture of corruption. When Yang Yun, the imperial advisor, discovered this, he was furious and took decisive action: he promoted only those with true talent and dismissed anyone incompetent, regardless of their wealth. He himself remained scrupulously honest, refusing all illicit gains and even distributing his parents' inheritance among his clan brothers.
However, Yang Yun, confident in his extraordinary talent, looked down on others, spoke without restraint, and delighted in exposing people's secrets, thus offending many.
Once, Dong Zhong, the Marquis of Gaochang, had his startled horses charge into Beiye Gate. Yang Yun remarked, "Previously, a carriage crashed into the palace, breaking the gate and killing the horse, and soon after Emperor Zhao died. Now this happens again—could history be repeating itself?"
Another time, Yang Yun heard that the Xiongnu chanyu was tyrannical and forced to suicide by his subordinates, so he remarked, "A tyrant is bound to perish. If the Qin dynasty had appointed capable officials, it would still be thriving today. Past and present are all jackals of the same lair!"
In the feudal society of the time, such words could not be spoken; fortunately, no one reported him, so Yang Yun remained safe and sound.
In 55 BC, Emperor Xuan's trusted advisor Changle was suddenly summoned for interrogation. Suspecting Yang Yun had informed against him, Changle reported Yang Yun's past seditious remarks to the emperor. Hearing this, the emperor flew into a rage but, recalling Yang Yun's former merits, could not bear to execute him—merely stripping him of his official rank and reducing him to commoner status.
After Yang Yun was dismissed from office and returned home, he believed his words and actions were not wrong. So, he purchased vast lands, gathered many guests, and spent his days in leisure. His friend Sun Huizong advised him, "You should reflect on your mistakes behind closed doors, or else disaster will come."
Yang Yun, filled with pent-up resentment and nowhere to vent it, immediately wrote a letter to Sun Huizong upon hearing his words, the letter brimming with extreme dissatisfaction toward the court. Soon, someone reported this to the authorities, and the letter was discovered. Emperor Xuan was furious and ordered Yang Yun executed.
Later, people used the idiom "jackals from the same lair" to describe those of the same ilk.
Source: *Book of Han*, "Biography of Yang Yun"
Meaning of the Idiom: Later, the Chinese idiom "一丘之貉" came to describe those of the same ilk.