The Alliance of the Jianzhong era(建中會盟) refers to a series of three alliance ceremonies concluded between the Tang dynasty and Tibet(吐蕃) in the year 783: first in January at Qingshui(淸水), then in July at Changan(長安), and later in Lhasa(拉薩). Previous studies have interpreted this as a diplomatic response to the Rebellion of the Four Self-Proclaimed Kings(四王). However, this study reinterprets the Jianzhong alliance as the intended outcome of Emperor Dezong’s consistently pursued pro-Tibet foreign policy from the early years of his reign.
Emperor Dezong, after his accession to the throne, adopted a conciliatory policy toward Tibet and consistently dispatched envoys to conduct negotiations beginning in 780. In addition, after severing relations with the Uyghurs, Emperor Dezong strategically shifted to a Tibet-centered diplomatic policy. In December 781, the Tang court applied the Jiushengli(舅甥禮) and demarcated the border along the Helan Mountains(賀蘭山). The schedule for the alliance treaty had already been finalized prior to September 782. These conditions were concretely reflected in the first alliance treaty concluded at Qingshui in the first month of Jianzhong 4(783), which formalized Tibetan control over the Hexi(河西) and Longyou(隴右) regions and included unfavorable terms for the Tang, such as the establishment of a buffer zone(閑田) along the Tang–Tibet border. Therefore, the Jianzhong alliance was a predetermined diplomatic outcome of Emperor Dezong’s pro-Tibet foreign policy, which he had pursued since the beginning of his reign.
However, the series of military rebellions within the Tang dynasty in 782, along with the Rebellion of the Four Self-Proclaimed Kings that broke out in November, weakened the Tang’s negotiating position and became a factor that led to the acceptance of even more unfavorable terms in the Jianzhong alliance. In other words, the Jianzhong alliance was an event that embodied both the continuity and the turning point of Emperor Dezong’s diplomatic line in the early years of his reign.