During the reign of Emperor Ping of the Han Dynasty, the Grand Empress Dowager ruled as regent while her nephew Wang Mang, a member of the imperial clan, took control of the government and was granted the title Marquis of Xindu.
Wang Mang, seeking to boost his personal prestige, ordered the Xiongnu Chanyu to send Wang Zhaojun's daughter, Xubu Juciyun, to serve the Empress Dowager, promising the Chanyu lavish gifts in return.
The kings of the Later Cheshi and Quhulai kingdoms in the Western Regions, resentful of the oppression by the Han-appointed Protector-General, fled with their people to seek refuge under the Chanyu of the Xiongnu. The Han court promptly sent a stern message to the Chanyu: "The treaties established by Emperors Xiaoxuan and Xiaoyuan decree that all subjects south of the Great Wall answer to Han, while those north of it answer to the Xiongnu. These two Western Region kings fall under Han jurisdiction. You must hand them over immediately, without fail."
The Chanyu said, "My father, Huhanye Chanyu, left a dying wish that those who defected from China should not be taken in, but the two kings of the Western Regions are foreigners, so it is harmless to accept them."
Wang Mang, by detaining Xubu Juyun and demanding the return of gifts as leverage, forced the Chanyu to reluctantly hand over the two kings of the Western Regions, but he begged the Han to show them mercy. The Han envoy then summoned all the kings of the Western Regions and, in front of everyone, executed the King of Cheshi Rear and the King of Quhulai. The envoy then read out four new rules: the Chanyu could not accept any Han Chinese, Wusun people, or those from the Western Regions who had been enfeoffed by China who fled to the Xiongnu. The Chanyu was deeply displeased, arguing that this was a unilateral revision of the treaty by the Han, showing no respect for Xiongnu interests.
Wang Mang then demanded that the Xiongnu chanyu adopt Chinese customs by changing his original name "Nangzhiyasi" to the single-character name "Zhi." After usurping the throne and renaming his dynasty "Xin," Wang Mang insisted on a fresh start, sending envoys bearing a new seal to replace the Xiongnu king's old one. The old seal bore the inscription "Seal of the Xiongnu Chanyu," while the new one read "Seal of the Xiongnu Chanyu of Xin."
The Xiongnu king, unable to read Chinese characters, handed over the old seal with a puzzled expression and returned to his yurt wearing the new seal and ribbon. The Han envoy discussed, "Once the Xiongnu king deciphers the inscription on the new seal, he will likely demand the old one back. Better to smash the old seal now and dash his hopes."
The next day, the Xiongnu king indeed reneged, declaring, "My old seal was called a 'xi,' bearing no Chinese script; the new seal is called a 'zhang,' using Chinese characters. A 'xi' is a ruler's seal, while a 'zhang' is a minister's seal. The new seal is no different in rank from my subordinates' seals. I demand the old one back." When he learned the old seal had been destroyed, the Xiongnu king tossed the new seal to the ground and stalked off in fury.
After suffering several defeats, the Xiongnu king grew convinced the Han court was deliberately toying with him. When defectors arrived from the Wuhuan, the Chanyu immediately ordered his forces to ignore Han regulations and accept the surrendering troops. The Wuhuan set the precedent, and one by one, the other western marquises and kings followed suit, rebelling against the Han and forming an alliance with the Xiongnu.
The Western Regions were in constant turmoil
Wang Mang, confident in his overflowing treasury, decided to teach the Xiongnu chanyu a lesson by planning to mobilize 300,000 troops with a year's worth of supplies, splitting them into ten columns, and vowing to crush the Xiongnu.
General Yan You advised Wang Mang, "The Xiongnu threat has plagued us for ages; even the Zhou emperors and Qin Shi Huang could not subdue them. Emperor Wu of Han selected generals, trained troops, and deployed both cavalry and infantry, draining the empire's wealth to strike deep into Xiongnu territory. Though he won many battles, the treasury was emptied, and the conflict dragged on for over thirty years. I believe we should not launch a massive campaign against the Xiongnu. Instead, we should selectively defeat a few tribes to curb their arrogance."
Wang Mang ignored advice, mobilized troops and requisitioned grain, throwing the realm into turmoil and ultimately sparking the great chaos at the end of the Western Han Dynasty. "War and calamity intertwined" refers to endless years of conflict with disasters following one after another.
Source: *Book of Han*, "Biography of the Xiongnu, Part Two"
Meaning of the Idiom: Later, the Chinese idiom "兵连祸结" came to describe endless years of conflict with disasters following one after another.