Emperor Gaozu of Tang allowed the assassination of a khagan of the Western Turkic Khaganate by Eastern Turkic rivals, one of the earliest events in the Tang campaigns against the Western Turks. Emperor Gaozu of Tang: Emperor Gaozu of Tang, personal name Li Yuan, courtesy name Shude, Xianbei name Daye Yuan, was the founding emperor of the Tang dynasty of China, reigning from 618 to 626 CE. Under the Sui dynasty, Li Yuan was the governor in the area of modern-day Shanxi, and was based in Taiyuan. November 2, 619. Wiki link