Zhangsun Cheng (长孙晟, 551–609): Sui Dynasty Diplomat and General

The article is devoted to the biography and activities of the outstanding Sui diplomat and commander Zhangsun Cheng, who played a key role in the relations between the Eastern Turkic Khaganate and the Sui Empire. After the unification of China under the rule of the Sui dynasty, the new Qaghan of the Turks (Shetu) began an active military campaign against China (582), for which the Sui Empire was not ready. In order to build further relations with the Eastern Turks, Emperor Yang Jian attracted the most experienced diplomats from his entourage, who knew the strengths and weaknesses of the Eastern Turks. One of them turned out to be Zhangsun Cheng, who had previously been on diplomatic missions with the nomads many times. The Chinese diplomat, using his connections and acquaintances in the Khaganate, entered into secret negotiations with the closest circle and relatives of Qaghan Shetu, as a result of which many of them went over to the side of Sui China (Abo and Chulokhou). As a result of his activities, Zhangsun Cheng contributed to the split of the Eastern Turkic Khaganate into two camps – western and eastern, its weakening and the conclusion of a vassal agreement between the Turks and Sui China in 584. Zhangsun Cheng was entrusted with the next task in 593, when information appeared at the court of the Sui emperor about the impending rebellion against the empire with the participation of the new ruler of the Turks – Dulan Qaghan and his wife Princess Da-yi. Cheng went on a mission to the Turks, as a result of which he brought discord into the personal relations of the Qaghan and his wife. He caught Princess Da-yi in treason with the high-ranking Sogdian An Suijia, and later planned her murder, since she posed a threat to the empire due to her desire to unite the efforts of the Western and Eastern Turkic Khaganates against the Sui Empire. Later, Cheng initiated the creation of an alternative political center on the territory of the Khaganate under the leadership of Qimin Qaghan, as a result of which the Sui Empire secured its northern borders for many years (until 609) and received a controlled neighbor in the person of the northern nomads.