The Fragile Peace of Heqin

From the founding of the Western Han Dynasty under Emperor Gaozu (Liu Bang), China pursued a policy of heqin (marriage alliances) to maintain peace with the nomadic Xiongnu confederation. The Han court would send noblewomen—typically daughters of vassal kings—to marry Xiongnu chanyus (rulers), accompanied by artisans, servants, and lavish gifts including silk, wine, and grain. This tributary system temporarily satisfied Xiongnu demands, reducing raids along the northern frontier.

When Emperor Wen ascended the throne in 180 BCE, he continued this strategy. However, in 177 BCE, Xiongnu forces under the Right Worthy King invaded the Hetao region south of the Yellow River, slaughtering and pillaging. Though Emperor Wen mobilized 85,000 cavalry to repel them, he still acquiesced to renewed heqin negotiations after the Xiongnu falsely blamed the conflict on Han provocation. This pattern of Xiongnu aggression followed by Han appeasement set the stage for a catastrophic betrayal.

The Eunuch Who Changed History

The crisis began in 174 BCE when the aging Modu Chanyu died, succeeded by his son Jiyu, titled the “Old Shang Chanyu.” As part of renewed heqin ceremonies, Emperor Wen assigned a palace eunuch named Zhonghang Yue to escort the latest Han “princess” to the Xiongnu court. Unlike previous envoys, Zhonghang—a capable but embittered man from Yan—vehemently resisted this exile. Forced into service, he swore vengeance: “If I must go, I will become Han’s greatest calamity.”

Upon arriving in the steppes, Zhonghang defected to the Xiongnu. His intimate knowledge of Han court politics and military logistics made him invaluable to Old Shang Chanyu. What followed was a masterclass in cultural sabotage:

1. Economic Warfare
Zhonghang recognized the Xiongnu’s growing dependence on Han silk and foodstuffs. He convinced the chanyu to reject these goods, demonstrating how silk garments tore easily during horseback raids compared to traditional leather. By severing this economic lifeline, he deepened Xiongnu self-sufficiency and hostility.

2. Administrative Modernization
He introduced Chinese writing systems to help the Xiongnu track populations and livestock—a pragmatic reform aimed at strengthening their nomadic state against Han.

3. Psychological Provocations
Zhonghang orchestrated petty diplomatic slights, such as having the Xiongnu use longer bamboo slips for correspondence than Han envoys and adding grandiose prefixes like “Heaven-born, Sun-and-Moon-Appointed” to the chanyu’s titles. These calculated insults stoked tensions.

4. Military Advising
Most dangerously, he guided Xiongnu raids using his knowledge of Han border defenses. In 166 BCE, his counsel enabled a devastating 140,000-strong Xiongnu cavalry incursion that reached within 200 km of the Han capital, burning imperial palaces at Pengyang.

The Unraveling of an Era

Zhonghang’s treachery transformed the heqin policy from a peacekeeping tool into a geopolitical liability. The historian Sima Qian recorded how Han statesman Jia Yi fantasized about “binding the chanyu’s neck and flogging Zhonghang’s back”—a testament to the eunuch’s infamy.

When Old Shang died circa 160 BCE, his son Junchen continued the raids. Emperor Jing (r. 157–141 BCE) managed temporary stability through renewed heqin and border markets, but the underlying tensions remained. By the time the young Emperor Wu took power in 141 BCE, Han China had spent seven decades rebuilding its economy and military. The stage was set for a reckoning.

The Road to War

Three factors drove Emperor Wu’s eventual abandonment of heqin:

1. Economic Resurgence
Decades of recovery had filled Han granaries to bursting, with state coffers so overstuffed that “counting strings of coins snapped from rot.” The Han military now boasted abundant warhorses and advanced crossbow technology.

2. Strategic Imperatives
As scholar Chao Cuo had warned earlier, the Xiongnu’s nomadic mobility made them impossible to control through diplomacy alone. Their cyclical raids—tolerated during Han’s post-war recovery—became intolerable as Han power grew.

3. National Humiliation
Zhonghang’s betrayal and the Xiongnu’s repeated treaty violations (like their attempted alliance with rebel kingdoms during the 154 BCE Wu-Chu Rebellion) cemented Emperor Wu’s resolve.

The final debate came in 135 BCE when Xiongnu requested another heqin marriage. At court, Minister Wang Hui argued for war, citing Xiongnu perfidy, while Grandee Secretary Han Anguo warned of the perils of campaigning across the steppes. Though most officials favored Han’s cautious approach, Emperor Wu’s subsequent 44-year war against the Xiongnu proved where his true sympathies lay.

Legacy of a Traitor

Zhonghang Yue’s story encapsulates the perils of coerced diplomacy and personal vengeance intersecting with statecraft. His actions:
– Exposed the fragility of heqin as a long-term solution
– Accelerated the militarization of Han-Xiongnu relations
– Demonstrated how individual actors could alter the course of history

Modern scholars still debate whether Zhonghang was a spiteful traitor or a tragic figure—a mutilated man weaponized by empire. Either way, his betrayal marked the end of an era, paving the way for the Han-Xiongnu Wars that would redefine East Asian geopolitics.