Emperor Wu’s Attempted Trap For The Xiongnu At Mayi


The predecessors of Emperor Wu (r. 141-87 BCE) usually took a defensive approach to dealing with the Xiongnu confederation of tribes that lived in the eastern Eurasian Steppe. Previous emperors often resorted to tribute payments, marriages and trade to keep the populous nomads happy, usually only martialing their armies against the Xiongnu on occasions when the nomads raided imperial territory. Emperor Wu, although he initially followed the precedent of peace and tribute, eventually decided to shift the Han Empire’s foreign policy with the Xiongnu from a defensive stance to a state of active hostility.

Emperor Wu’s first move against the Xiongnu occurred in 134 BCE. The plan must have been in the works for a long time, for it all hinged on an agent of the emperor named Nie Wengyi who had gone to the Xiongnu and built trust with them by playing the role of a smuggler. By trading contraband to the Xiongnu, Nie Wengyi came to be known and trusted by various nomad leaders, and around 134 BCE, he had finally gained the ear of the Xiongnu leader, the Shanyu. With the agent finally in position, the emperor could move into the final phases of the plan.

When the time was right, Nie Wengyi was instructed to offer the Shanyu a fateful proposal. Following an order from the Han government, Nie Wengyi went to the Shanyu and offered to help the Xiongnu take the wealthy city of Mayi, in Yanmen province. The agent apparently claimed that he could offer the Shanyu a variety of routes to securing Mayi.  He claimed that he could assassinate the high officials to disorganize the town, and he further proposed that he would likely be able to convince the city of Mayi to surrender to the Xiongnu peacefully once the loyal officials were dead. Nie Wengyi’s deep-cover relationship-building paid off, for the Shanyu responded to the plan with eager excitement instead of caution. Yet, the Xiongnu leader did make one condition—Nie Wengyi needed to assassinate the officials in Mayi before the Xiongnu would make their move. To prove that the officials were dead, Nie Wengyi was told to hang their decapitated heads from the city walls for Xiongnu spies to see.

With his mission near completion, Nie Wengyi returned to Mayi and updated all those involved in the plot on his progress. Presumably after waiting enough time for the emperor to prepare, Nie Wengyi eventually made true his promise to hang some heads on the city wall. Yet, instead of government officials, the heads belonged to local condemned criminals. When the Xiongnu spies in the region reported to their leader that there were indeed heads hanging from the walls of Mayi, the Shanyu quickly pulled together a force reportedly numbering 100,000 horsemen and crossed into Han territory at Wuzhou.

The Shanyu’s enthusiasm, however, soon began to give way to caution as he ventured further into Han territory. His concerns especially began to increase when he noticed that the countryside was eerily absent of human activity. There were no farmhands, travelers, or loitering commoners to be seen. Animals, however, were apparently roaming free and left untended in the fields. Unnerved by the sight, the Shanyu delayed his advance against Mayi and instead attacked a signal beacon station in Wuzhou. Unlike the rest of the countryside, the Xiongnu found the station still inhabited, and, as luck would have it, they managed to find and capture a local defense official in the station.

Unfortunately for Emperor Wu, the captured official knew something of the emperor’s plan at Mayi and, under interrogation, he told the Xiongnu everything he had heard. The Shanyu was shocked to learn that the seemingly empty region his horsemen were traveling through was actually in no way devoid of life. The eerie ghost town atmosphere was caused by the commoners being quarantined to their communities. Yet, despite the absence of the commoners, the Shanyu discovered that the region around Mayi was much more overpopulated than it appeared—according to Sima Qian (c. 145-90 BCE), Emperor Wu had preemptively hidden over 300,000 Han troops in the valleys around Mayi, hoping to trap the Xiongnu when they began to enter the city. In addition, yet more troops were coming from the region of Dai to attack the Xiongnu baggage train.

Tipped off to the danger, the Shanyu immediately led his forces out of Han territory. The section of the Han forces sent from Dai to attack the baggage train of the Xiongnu could have possibly cut off the Shanyu’s retreat, but when they learned that they would not be fighting just the baggage train, but the whole Xiognu horde, the warriors from Dai refused to fight. With the trap at Mayi thwarted, and the division from Dai purposefully keeping out of the way of the Xiongnu, the Han forces could only pursue the invaders to the border without inflicting any damage on their foe. It was an embarrassing debacle that eventually caused Wang Hui, one of the masterminds behind the trap, to commit suicide.

Written by C. Keith Hansley

Picture Attribution: (scene of the Chinese Campaign against Annam (Vietnam) 1788 – 1789, painted by a collaboration of Chinese and European painters c. late 18th century, [Public Domain] via Creative Commons).


  • Records of the Grand Historian (Shi ji) by Sima Qian, translated by Burton Watson. New York: Columbia University Press, 1993.

Leave a Reply