Research Report on the Sazhou-Guidang Incident (PS5 blood message story)

1. Background and Time/Location of the Incident

The Sazhou-Guidang Incident occurred in the mid-9th century, specifically in 848 CE (2nd year of the Dazhong reign under Emperor Xuānzong of Tang), in what is now Dunhuang, Gansu Province. The region known as Shazhou referred to the area around Dunhuang and was part of the strategically significant Hexi Corridor that had been under the control of the Tibetan Empire (Tubo) since the late 8th century. After the An Lushan Rebellion (755–763), the weakened Tang Dynasty lost control of the region, and by the 790s, Dunhuang and surrounding areas had fallen to Tibetan rule. In 842, internal succession struggles within the Tibetan Empire led to severe weakening of their power, loosening control over distant territories like Dunhuang, which fell into a de facto state of anarchy. Against this backdrop, the residents of Dunhuang rose up without assistance from the Tang court, expelled the Tibetan forces, and voluntarily returned the region to Tang authority. This event became known as the Sazhou-Guidang (Return of Shazhou to Tang).

2. Key Figures and Their Roles

The central figure of the incident was Zhang Yichao, a Han Chinese local elite from Dunhuang. His father, Zhang Qianyi, had served as a governor under Tibetan administration, giving the family deep familiarity with local governance. Discontent with Tibetan rule, Zhang Yichao rallied both Han Chinese and local ethnic groups including Uyghurs, Tuyuhun, and Qiang tribes. In 848, he launched an uprising with their support. The Tibetan garrison fled without resistance, allowing Zhang to take control of Dunhuang. He declared himself acting governor (刺史) and sent envoys to the Tang imperial court to declare his allegiance.

The Tang court welcomed Zhang’s submission. Emperor Xuānzong, who was then working to restore imperial order after years of turmoil, recognized Zhang’s achievements. In 851, Zhang’s brother Zhang Yitan traveled to Chang’an with maps and census records of 11 prefectures Zhang had brought under control. In response, Emperor Xuānzong officially appointed Zhang Yichao as Defender of Shazhou and established a new military command—the Guiyijun (Circuit of Return to Righteousness)—naming Zhang as its Jiedushi (military governor). Tibetan forces, weakened by civil strife, were unable to retaliate, and local support for Zhang solidified his rule.

Other notable figures include Emperor Xuānzong of Tang, who formally conferred titles upon Zhang Yichao. Zhang’s brother Zhang Yitan served as a diplomatic liaison with the Tang court, and his nephew Zhang Huai-shen would later inherit leadership of the Guiyijun and continue relations with the Tang.

3. Course of the Incident and Political Context

The rebellion was swift. By September 848, Zhang had liberated Dunhuang. Between 849 and 850, he expanded his control, and by 851, he ruled over 11 prefectures: Guazhou, Yizhou, Xizhou, Ganzhou, Suzhou, Lanzhou, Shanzhou, Hezhou, Minzhou, and Kuozhou. This effectively restored Tang presence in vast areas of what are now Gansu, eastern Qinghai, and western Xinjiang. Though these territories were nominally returned to Tang, Zhang retained autonomous control while maintaining formal allegiance.

The broader context reveals that Tang, suffering from internal rebellions and decentralization since the 8th century, was too weak to project direct power into the far west. Conversely, Tibet had peaked in the late 8th century but began to collapse in the 840s due to internal divisions. When its emperor was assassinated in 842, the empire fragmented, creating an opportunity for local powers like Zhang Yichao to assert independence.

Meanwhile, the 9th-century East Asian geopolitical landscape was relatively stable. Tang maintained peaceful relations with both Balhae and Unified Silla. Balhae had resumed diplomatic exchanges and was thriving during its so-called “Golden Age of the East Sea.” Silla also maintained amicable ties with Tang and benefited from maritime trade led by figures like Jang Bogo. Thus, the Sazhou-Guidang event did not provoke regional conflict but rather contributed to temporary geopolitical stability.

4. Political and Diplomatic Impact

For Tang, the incident was hailed as a rare success. It enabled Tang to reassert nominal sovereignty over parts of the Hexi Corridor. This symbolic victory bolstered imperial prestige and allowed Tang to reopen portions of the Silk Road, facilitating trade and Buddhist pilgrimage routes. Strategically, regaining this buffer zone helped curb further Tibetan or Uighur incursions.

However, Tang’s influence was limited to titles and recognition. It provided no troops or financial aid to Zhang Yichao. The Guiyijun was effectively an autonomous regime, with Zhang exercising local authority while upholding Tang legitimacy. Zhang and his successors maintained this façade of loyalty until the fall of the Tang Dynasty in 907, after which the regime persisted for decades with near-complete independence.

For neighboring states, the impact was minimal. Tibet, having lost Dunhuang, continued to decline and ultimately disintegrated. Balhae saw no strategic loss or gain but viewed Tang’s westward recovery as a stabilizing force. Silla likewise was unaffected, but the restored safety of overland routes may have indirectly benefited Silla monks and traders. Overall, the event reinforced peaceful relations without altering diplomatic alignments.

5. Geographic Scope and Strategic Significance

Shazhou referred to present-day Dunhuang, located in the Hexi Corridor, a narrow belt of land between the Gobi Desert and Qilian Mountains. This corridor was the vital overland link between China and Central Asia. During the Tang’s high point, the area had been controlled through the Anxi Protectorate and the “Four Garrisons of Anxi.” By the late 8th century, the region was lost to Tibet.

Zhang’s reconquest included not only Dunhuang but also 10 adjacent prefectures stretching from central Gansu to eastern Xinjiang and Qinghai. This area held immense economic value due to Silk Road trade and military value as a western frontier. It was also crucial for Buddhist transmission, serving as a conduit for pilgrims and texts between China and India. The reestablishment of order enabled the flourishing of religious and cultural activity, exemplified by new construction at Mogao Caves during Zhang’s rule.

The phrase “Four Garrisons” (四鎭) referenced Tang military outposts originally in Kucha, Kashgar, Karghalik, and Hotan. While Zhang’s territories were east of these, the expression “Four Garrisons Return to Tang” was used symbolically to evoke the restoration of Tang’s western frontier.

6. Modern Historiographical Interpretation

Historians long neglected Zhang Yichao due to limited mentions in official dynastic histories. He lacks a dedicated biography in the Old Tang Book or New Tang Book, and his achievements are only noted in imperial annals. However, 20th-century archaeological finds, especially at Mogao Cave 156, including wall inscriptions and murals depicting Zhang and his wife, have reshaped scholarly opinion.

Modern scholars debate whether the Guiyijun was an independent kingdom under the guise of loyalty or a genuine example of decentralized but faithful Tang governance. Some argue that Zhang’s regime had its own administrative system and survived well beyond the Tang’s fall, suggesting effective sovereignty. In 908, Zhang’s son Zhang Chengfeng even declared a new state, the Western Han Kingdom of Jinshan, underscoring its independence.

Others view Zhang as a model of Confucian loyalty, who, despite having the power to secede, chose to align with Tang for the greater good. His decision to return Dunhuang voluntarily to the empire stands out in Chinese history as an act of political restraint and moral commitment. His regime’s stability brought peace to the Hexi Corridor, enabling cultural coexistence and religious revival.

In conclusion, the Sazhou-Guidang incident marks one of the final triumphs of Tang expansionism, even if symbolic. It illustrates both the fragmentation and regional dynamism of late Tang China. Zhang Yichao remains a rare case of a warlord who prioritized order and allegiance, earning him lasting recognition in modern historiography.