The Khitan (Liao) Dynasty: A Strategic Variable in Northern China during the Five Dynasties and Early Song, with Contextual Analysis within the Xuzizhi Tongjian

Brief Introduction

In the chaotic chess game of the Five Dynasties and Ten Kingdoms period, Liao (Khitan) was not only the greatest northern threat to the Central Plains dynasties but also a critical geopolitical force determining the succession of regimes. As a northern nomadic-agricultural hybrid empire established by the Khitan people, Liao possessed a strong cavalry advantage during the early Song period. More significantly, by supporting breakaway regimes such as the Northern Han, it deeply intervened in the struggles for control of the Central Plains. While historical sources such as the Xuzizhi Tongjian (Continuation of the Comprehensive Mirror to Aid in Government) primarily focus on Song-Liao relations, their context often includes records from preceding dynasties—particularly the confrontation between Later Zhou and the Khitans. These records provide essential background for understanding the border defense challenges faced by the early Northern Song.

Core Knowledge Points

1. The Rise of Khitan and Military Characteristics

The Khitan people originated from the Northeast Asian grasslands and were skilled in nomadic warfare, combining high mobility with predatory tactics. In 907, Yelu Abaoji established the Khitan political entity (later changing the state name to Liao), rapidly unifying the northern tribes. By the Five Dynasties period, Liao had developed into a state with a "semi-agricultural, semi-pastoral" structure, possessing a mature bureaucratic system and powerful cavalry corps.

2. The "Khitan-Northern Han" Strategic Alliance

Liao maintained long-term dependent or allied relations with Later Jin and the Northern Han. In particular, the Northern Han, a regime controlling Shanxi, served as Liao’s forward outpost for projecting power into the Central Plains. Liao ruler Yelu Dejian once used the Northern Han as a passage to advance south, even briefly entering Kaifeng, an event known as the humiliation of the "Child Emperor." This strategy of "supporting the primary via branches" allowed Liao to continuously apply military pressure without the need for large-scale direct troop deployment in the Central Plains.

3. Direct Conflict with Later Zhou: Prelude to the Battle of Gaoping

During the Later Zhou period, Liao frequently supported the Northern Han in launching military incursions. Around the time of Zhou Shizong Chai Rong’s ascension, the confrontation with Liao was most intense. Liao attempted to use the Northern Han to clamp down on Later Zhou from both sides. However, Zhou forces, relying on disciplined infantry formations and proto-firearms, checked the Khitan southward advance in key battles. This phase of attrition warfare laid the groundwork for the early Northern Song’s border defense doctrine of "strength in the interior, weakness in the exterior" (shou nei xu wai).

Connection to Xuzizhi Tongjian and the Historical Context

Although the Xuzizhi Tongjian primarily records Northern Song history (960–1279), its opening chapters and background narratives often look back at the historical flow from the late Five Dynasties to the early Northern Song.

1. A Historical Turning Point: When describing the early border defense strategies of Song Taizu (the first Northern Song emperor), the text references the historical legacy of the previous dynasty (Later Zhou) failing to resolve the Khitan threat completely. Liao’s support of the Northern Han directly caused the stagnation of the Northern Song’s unification war in the Shanxi direction, leading to a "Song-Liao-Han" three-way standoff.
2. Influence on Strategic Thinking: The records of early Song policies toward Liao in the Xuzizhi Tongjian (such as diplomatic maneuverings before and after the Chanyuan Treaty) trace their underlying logic back to military interactions between Later Zhou and the Khitans. Understanding Liao’s behavioral patterns during the Five Dynasties helps readers grasp the continuity and compromises in Northern Song border policies as presented in the text.
3. Cross-Verification of Sources: By combining the Zizhi Tongjian (compiled by Sima Guang, not Ouyang Xiu—note: Ouyang Xiu compiled the New Book of Tang and the New Book of Song, while Sima Guang compiled the Zizhi Tongjian) with the Xuzizhi Tongjian, we can fully reconstruct the process from "Khitan destruction of Jin" to "Song-Liao coexistence." Liao was not merely an external enemy, but a "second engine" that shaped political directions in the Central Plains during the Five Dynasties.

Conclusion

The existence of the Liao (Khitan) regime during the Five Dynasties and early Song profoundly altered the political geography of China. It was both an independent empire and the greatest obstacle to the unification of the Central Plains dynasties. By examining its role within the context of the Xuzizhi Tongjian, we can not only see the vulnerability of early Song border defenses but also better understand the interactive logic between the Central Plains agricultural civilization and the northern nomadic civilization that spanned hundreds of years.