Yan Border Forces

Guardians of the frozen north, holding the line until 222 BC.

via Wikipedia: Yan (state) · see source

The Yan Border Forces were the military defenders of the State of Yan, an ancient realm that stood as one of the last independent powers during the Warring States period. Positioned as the northernmost Chinese state, their primary duty was to shield the kingdom from incursions by steppe nomads while managing rivalries with southern states like Zhao and Qi. At its height, the state stretched from the Yellow River to the Yalu River, necessitating a robust defense system that included the construction of great walls along new northern borders. These forces were instrumental in establishing five commanderies—Shanggu, Yuyang, Youbeiping, Liaoxi, and Liaodong—to secure the frontier against the Donghu. Their existence was defined by the constant threat of invasion from both nomadic tribes and the rising power of Qin.

Quick Facts

Affiliation: State of Yan
Region: Northern Warring States (Shanxi to Liaodong)
Status: Conquered by Qin in 222 BC

Lore & Background

Yan's military doctrine was shaped by its unique geography and the constant pressure from northern nomads. Unlike states in the Central Plains, Yan faced a reality where defensive formations had to be solid yet flexible enough to handle rapid threats. The historian Wu Qi noted that "The Yan are a sincere and straightforward people... thus they excel in defensive positions, but are immobile and inflexible." To counter this, tactics involved applying pressure with small attacks and retreating rapidly to confuse their ranks. General Qin Kai expanded the kingdom's frontiers nearly one thousand kilometers east to the northwestern Korean Peninsula by launching campaigns against the Donghu and Gojoseon. This expansion led to the construction of a Great Wall on Yan's new northern borders. The forces also utilized currency shaped like knives, a form closely associated with nomads, suggesting deep commercial and tactical integration with the steppe tribes they fought.

Reader's Guide

The State of Yan operated under a feudal system where regional lords contributed troops, though leadership could shift based on wartime merit, as seen when King Zhao plotted with Zhao, Qin, Han, and Wei to launch a joint expedition against Qi. The Border Forces were specifically tasked with defending the mountainous borders in the west between Zhao and Yan, an area that often saw clashes resulting in stalemates requiring outside intervention. A pivotal moment occurred in 314 BC when Qi invaded during a succession crisis started by King Zikuai's symbolic resignation to Minister Zizhi. Although Qi practically conquered the country in months, a revolt driven by the misconduct of Qi troops restored Yan's borders. Later, under General Yue Yi, Yan achieved a massive victory, capturing most of Qi's seventy walled cities within a year. However, strategy relied heavily on specific terrain advantages; as Wu Qi advised opponents: "Attack the rear as well where and when they least expect it... use our armored chariots to set ambushes." Ultimately, survival depended on these defensive adaptations until the final Qin conquest.

Did You Know?

In 227 BC, Crown Prince Dan sent the assassin Jing Ke to kill the King of Qin in Xianyang, an act that precipitated Yan's final destruction.
Yan was the third-to-last state to fall to Qin, finally overrun in 222 BC, just one year before the declaration of the Qin Empire.