The Rise of Two Empires in 7th Century Asia

The 7th century witnessed the emergence of two formidable powers in Asia: the Tang Empire in China and the Tibetan Empire under Songtsen Gampo. When 13-year-old Songtsen Gampo inherited the throne from his father Namri Songtsen, he quickly consolidated power through decisive actions against rebels and implemented sweeping reforms. After conquering the Zhangzhung kingdom – the last obstacle to his expansion into Qinghai – the young ruler turned his ambitions toward the strategic Qinghai region, setting the stage for confrontation with the mighty Tang Empire.

This geopolitical tension had its roots in the earlier unification of Tibet under Songtsen Gampo’s ancestors. The Yarlung Valley, cradle of Tibetan civilization, saw the gradual expansion of the Yarlung tribal confederation led by the powerful Sribrtsanpo clan. By moving their capital to the Lhasa River valley and absorbing surrounding territories, they laid the foundation for what would become the Tibetan Empire.

The Precarious Position of the Tuyuhun Kingdom

Caught between these two expanding empires was the Tuyuhun kingdom, a nomadic state established by the Xianbei Murong clan around Qinghai Lake. Founded in the 4th century after a fraternal dispute within the Murong clan, Tuyuhun had grown prosperous through its advanced agriculture, horse breeding (notably the famed “Qinghai Cong” horses), mining, and strategic position along the Silk Road.

However, by the 7th century, internal decay and external pressures weakened Tuyuhun. In 634 CE, Tang Emperor Taizong launched a punitive expedition against Tuyuhun for border raids, appointing veteran general Li Jing to lead the campaign. The Tang victory reduced Tuyuhun to vassal status, though subsequent internal revolts required further Tang intervention to install the pro-Tang ruler Murong Nuohebo.

Diplomatic Maneuvers and Early Conflicts

The Tang-Tibetan relationship began with diplomatic exchanges in 634, but tensions escalated when Songtsen Gampo, angered by the Tang’s refusal of his marriage proposal (while granting princesses to Turks and Tuyuhun), attacked Tuyuhun in 638. This led to the first direct Tang-Tibetan conflict at Songzhou, where Tibetan forces initially succeeded before being repelled by Tang counterattacks.

The 641 marriage alliance between Tang Princess Wencheng and Songtsen Gampo temporarily stabilized relations. However, the deaths of both Emperor Taizong (649) and Songtsen Gampo (650) removed key stabilizing figures. Power in Tibet passed to the young Mangsong Mangtsen, with real authority held by the influential Gar (Mgar) clan, particularly minister Gar Tongtsen Yulsung (known in Chinese as Lu Dongzan).

The Road to Dafeichuan

Gar Tongtsen pursued an aggressive expansionist policy, targeting Tuyuhun as the gateway to Qinghai. After initial setbacks like the 659 defeat at Wuhai, Tibetan forces eventually overwhelmed Tuyuhun in 663 with help from defectors, forcing Murong Nuohebo to flee to Liangzhou.

The Tang court debated intervention but remained divided. Meanwhile, Tibet prepared for larger confrontation. In 670, they struck decisively, capturing the strategic Anxi Four Garrisons in the Western Regions, severing Tang control over the northern Silk Road and threatening the Guanzhong heartland.

Emperor Gaozong responded by appointing veteran general Xue Rengui to lead a massive 100,000-strong expedition, ambitiously titled “Commander of the March to Lhasa,” signaling Tang intentions to strike at the Tibetan heartland.

The Battle of Dafeichuan (670 CE)

The campaign unfolded disastrously for the Tang. Xue Rengui’s plan called for a rapid strike force to attack Wuhai while Guo Daifeng guarded the supply base at Dafeichuan. However, Guo – resentful of serving under Xue – disregarded orders and advanced with the supply train. Tibetan commander Gar Tsenba (Lun Qinling) exploited this by first allowing Xue’s initial success, then ambushing Guo’s vulnerable supply column before surrounding Xue’s forces at Dafeichuan with overwhelming numbers.

Contemporary sources claim Tibetan forces numbered 200,000 initially, swelling to 400,000 – likely including many conscripts from conquered territories like Tuyuhun. The complete Tang rout marked one of the dynasty’s worst military defeats.

Military Systems Compared

The battle revealed strengths and weaknesses in both empires’ military systems. The Tang relied on its sophisticated fubing (garrison militia) system, with soldiers rotating between farming and military service. However, the system was already showing strains from land distribution issues.

Tibet’s military combined traditional tribal organization with innovative adaptations. Their administrative-military “ru” (wings) and “tongde” (thousand-household) units could mobilize large forces through the “great recruitment” system. Unique features included:

– Heavy use of subject troops from conquered areas
– Elite “Tiger and Leopard Army” core forces
– Sophisticated intelligence networks using sentry posts and spies
– Effective reward systems like military insignia (“yig tshang”) and land grants

Tibetan cavalry, equipped with high-quality chainmail and specialized weapons like slings (“urdo”), proved particularly formidable in high-altitude warfare.

Strategic Consequences

Dafeichuan’s aftermath reshaped regional geopolitics:

1. Tibetan Ascendancy: Complete control over Tuyuhun gave Tibet rich pastures and strategic depth. They established sophisticated administration over the region while keeping a puppet Tuyuhun king.

2. Tang Defensive Posture: The loss forced Tang to strengthen northwestern defenses, establishing new military commands like Heyuan and Jishi. The Anxi Protectorate wouldn’t be fully restored until 692.

3. Long-Term Rivalry: This marked the beginning of nearly two centuries of Tang-Tibetan conflict, with fluctuating fortunes until both empires declined in the 9th century.

Enduring Historical Significance

The Dafeichuan campaign illustrates several broader historical themes:

– The clash between sedentary and nomadic military systems
– The importance of the Silk Road in imperial competition
– How marriage alliances could both stabilize and complicate relations
– The role of individual leadership versus systemic factors in military outcomes

The battle also foreshadowed later patterns in Tibetan expansion – their ability to incorporate conquered peoples into military systems, and the Tang’s struggles to project power into high-altitude regions. These dynamics would continue shaping East Asian geopolitics long after both empires faded.