The Siege of Baideng: How Liu Bang Was Trapped by the Xiongnu in 200 BC

The Siege of Baideng: How Liu Bang Was Trapped by the Xiongnu in 200 BC

In the winter of 200 BC, Liu Bang, founder of the Han Dynasty and known to history as Emperor Gaozu, marched north against the Xiongnu and walked into a trap. For seven days and nights his vanguard was encircled on a hill called Baideng, near present-day Datong in Shanxi, cut off from the main body of his army in bitter cold. The emperor who had defeated Xiang Yu and unified the empire now faced capture or death at the hands of a nomadic confederation. The Siege of Baideng, recorded by Sima Qian in the Records of the Grand Historian, became the founding humiliation of the Han and the event that shaped its frontier policy for the next sixty years.

This article reconstructs what happened: the rise of Xiongnu power, the campaign that led Liu Bang into the trap, the encirclement itself, the strange escape attributed to a bribe, and the long marriage-alliance policy known as heqin that followed.

The Early Han Facing a Hostile North

When Liu Bang founded the Han in 202 BC, the empire was exhausted. Decades of war against the Qin and then the long struggle with Xiang Yu had drained its manpower and treasury. Sima Qian notes that the new emperor could not even find four horses of the same color to draw his carriage, and that ministers rode in oxcarts. The Han inherited a country that needed rest, not a new war.

To the north lay a very different power. The Xiongnu were a confederation of pastoral, horse-riding peoples occupying the steppe beyond the agricultural heartland. They had no walled cities to defend and no fixed harvest to protect. Their wealth was mobile, their armies were mounted, and their tactics favored raiding, feigned retreat, and rapid concentration. For a settled empire still recovering from civil war, this was an enemy that was difficult to pin down and dangerous to chase.

Modu Chanyu and the Rise of Xiongnu Power

The Xiongnu had become formidable under a single ruler, Modu Chanyu, who came to power around 209 BC. The accounts in the Records of the Grand Historian describe Modu as ruthless and disciplined. He is said to have seized rulership by killing his own father, the previous chanyu, after training his followers to shoot wherever he aimed his whistling arrow, conditioning them to absolute obedience.

Under Modu the Xiongnu expanded in every direction. They subdued neighboring steppe peoples, including the Donghu to the east and the Yuezhi to the west, and they pressed against the northern Chinese states. By the time Liu Bang founded the Han, Modu commanded a unified steppe empire with, by Sima Qian's account, a very large force of mounted archers. This was the most powerful nomadic state China had yet faced, and it sat directly on the Han's vulnerable northern frontier.

The Spark: Han Xin of Dai and the Defection at Mayi

The immediate cause of the campaign was trouble inside the Han's own ranks. Liu Bang had enfeoffed a general also named Han Xin, distinct from the famous strategist of the same name, as King of Dai, with his base near Mayi on the northern frontier. This region was constantly exposed to Xiongnu pressure.

In 201 BC the Xiongnu besieged Mayi. Han Xin sent repeated envoys to negotiate, which made Liu Bang suspect him of disloyalty. Fearing punishment, Han Xin surrendered Mayi and went over to the Xiongnu, joining them against the Han. His defection opened the northern passes and gave Modu an ally familiar with Han territory. Liu Bang could not let a frontier king defect to a foreign power, and in the winter of 200 BC he led a large army north in person to crush the revolt and drive back the Xiongnu.

Marching Into the Trap

Liu Bang's campaign began well. His forces defeated Han Xin's troops and pushed north through the cold, scattering the enemy and gaining confidence with each engagement. Modu, however, was practicing the classic steppe stratagem of the feigned weakness. As the Han advanced, the Xiongnu repeatedly fell back, hiding their strongest warriors and best horses and displaying only old men and thin livestock.

Liu Bang sent scouts ahead to assess the enemy. Most returned reporting that the Xiongnu looked weak and could be attacked. One envoy, Lou Jing, warned that this apparent weakness was bait, arguing that when two states go to war each tries to display its strength, so the deliberate show of feebleness must conceal an ambush. Liu Bang, already committed and eager for a decisive blow, dismissed the warning and reportedly had Lou Jing imprisoned for demoralizing the troops.

Confident and impatient, the emperor pushed ahead of his slower infantry and supply train with the fastest cavalry, racing to catch what he believed was a beaten enemy. It was exactly the mistake Modu had been waiting for.

Seven Days on Mount Baideng

When Liu Bang reached the area of Pingcheng, near modern Datong, Modu sprang the trap. A massive Xiongnu cavalry force, which the Records of the Grand Historian numbers at around 400,000 riders, suddenly appeared and surrounded the emperor on the high ground of Baideng before the main Han army could close the gap.

Sima Qian preserves a vivid detail of the encirclement. The Xiongnu cavalry were arranged by the color of their horses, with white horses on one side, gray-blue on another, black on another, and chestnut on the fourth, a display of organization and overwhelming numbers meant to break the defenders' will. The siege lasted seven days and seven nights. It was deep winter, and the cold was so severe that, by the traditional account, two or three out of every ten Han soldiers lost fingers to frostbite. Cut off from supplies and from the rest of the army, the trapped emperor could neither break out nor be relieved.

The Escape: Sima Qian's Account of Chen Ping's Stratagem

How Liu Bang escaped is the most famous and most uncertain part of the story. According to Sima Qian, the emperor was saved by a secret plan devised by his adviser Chen Ping. The historian himself notes that the details of the scheme were kept confidential and were not fully known, which is why the surviving version reads as half legend rather than documented fact.

The traditional account is this. Chen Ping had an envoy carry rich gifts in secret to the yanzhi, the principal wife of Modu Chanyu. Some versions add that the envoy showed her a portrait of a beautiful Chinese woman and hinted that, if the siege continued, the Han would present such a woman to the chanyu to win his favor, which would threaten the yanzhi's own position. Persuaded by the bribe and the warning, the yanzhi urged Modu to lift the siege. She is said to have argued that two rulers should not corner each other, that Han land would be of little use to a nomadic people, and that the gods might not favor holding the Han emperor.

There were also sound military reasons for Modu to relent. The Xiongnu had expected support from Han Xin's defected generals, who failed to arrive on schedule, raising Modu's suspicion of a trap of his own. With the main Han army approaching, Modu opened one corner of the encirclement. Sima Qian records that the Han troops marched out through the gap in heavy fog, crossbows drawn and double-loaded, ready to fire, and rejoined the main force without the Xiongnu pressing the attack. Liu Bang escaped with his life, but the campaign was a strategic defeat.

The Birth of the Heqin Policy

Baideng convinced Liu Bang that the Han could not defeat the Xiongnu by force in its weakened state. The man who supplied the alternative was Lou Jing, the same adviser who had warned against the trap and was now released and rewarded for his foresight.

Lou Jing proposed a policy that came to be called heqin, meaning peace through kinship. Its core was to marry a Han princess to the chanyu and send the Xiongnu regular annual gifts of silk, grain, wine, and other goods. The reasoning was partly strategic and partly cynical. Lou Jing argued that if the chanyu married a true Han princess and she bore a son, that son might one day become chanyu and would be, in some sense, a grandson of the Han emperor, binding the two ruling houses by blood over the generations. Liu Bang accepted the plan, though the accounts say his own empress, Lü, wept and refused to let their daughter be sent, so a woman of the imperial clan was dispatched as a princess instead.

How Heqin Worked in Practice

Heqin was less a true alliance than a system of managed appeasement. The Han sent a princess, an escort, and fixed yearly shipments of valuable goods, and in return the Xiongnu were expected to keep the peace along the frontier. The policy continued through the reigns of Gaozu, Hui, the Empress Lü's regency, Wen, and Jing, spanning roughly sixty years and involving repeated marriages and ever-larger gifts.

In practice the peace was partial and often broken. The Xiongnu accepted the goods and the brides yet continued to raid the border when it suited them, because raiding was woven into their economy and the gifts were never enough to replace it. During the reign of Emperor Wen, for example, large Xiongnu forces penetrated deep toward the capital region, and their signal fires could be seen from the imperial palaces, forcing the Han to mobilize defensive armies even while the marriage treaties remained nominally in effect. Heqin bought time and reduced the scale of conflict, but it never delivered the secure peace its name promised.

The Long-Term Significance of Baideng

The importance of the Siege of Baideng lies less in the battle than in everything that followed from it. The defeat established a basic strategic reality of the early Han: a settled, war-weary empire could not, for the moment, overcome a unified and mobile steppe power. That recognition produced the heqin policy, which traded wealth and imperial daughters for relative quiet on the frontier and bought the dynasty the decades of recovery it desperately needed.

That recovery, in turn, made a different future possible. The wealth and population the Han accumulated under the policy of restraint became the foundation on which a later ruler, Emperor Wu, would eventually build the armies that took the offensive against the Xiongnu. In this sense the humiliation at Baideng and the patient appeasement that followed were not simply a defeat but the opening move in a much longer contest between the agricultural empire and the steppe.

Baideng also entered Chinese cultural memory as a lasting symbol. It became the standard reference for the danger of advancing rashly, underestimating an enemy, and ignoring sound counsel, and the story of Chen Ping's secret stratagem became a famous example of winning by cunning what could not be won by force. The encirclement of a founding emperor by mounted archers fixed the Xiongnu in the Han imagination as a serious and enduring threat, shaping how the dynasty thought about its northern frontier for centuries.

FAQ

Q: When and where did the Siege of Baideng take place?

The siege took place in the winter of 200 BC at Mount Baideng, near Pingcheng, in the area of present-day Datong in Shanxi province. Liu Bang, Emperor Gaozu of the Han, was surrounded there by Xiongnu cavalry for seven days and nights before escaping.

Q: Who was Modu Chanyu?

Modu Chanyu was the ruler who unified the Xiongnu into a powerful steppe empire from around 209 BC. According to the Records of the Grand Historian, he seized power by killing his father and built a disciplined confederation of mounted archers that expanded across the steppe and became the early Han's most dangerous rival.

Q: How did Liu Bang escape from Baideng?

According to Sima Qian, Liu Bang escaped through a secret stratagem devised by his adviser Chen Ping, who sent gifts to bribe the yanzhi, Modu's principal wife, and persuade her to urge the chanyu to lift the siege. Sima Qian notes the details were kept secret, so this account is considered semi-legendary rather than fully documented.

Q: What was the heqin policy?

Heqin, meaning peace through kinship, was the policy the Han adopted after Baideng on the advice of Lou Jing. It involved marrying a Han princess to the Xiongnu chanyu and sending regular annual gifts of silk, grain, and wine in exchange for relative peace on the frontier. It lasted about sixty years through several reigns.

Q: Did the heqin policy actually bring peace?

Only partially. The Xiongnu accepted the brides and gifts but continued to raid the Han border when it suited them, since raiding was part of their economy. Heqin reduced the scale of conflict and bought the Han decades of recovery, but it never produced the complete security its name implied.