Sui Yangdi
As the Sui Dynastys power waned, separatist Chinese leaders agreed to become vassals of Shibi Qaghan (609-19) and adopted Turkic-style titles, as well as the Khaganate's wolf's-head banners. In 615, the Chinese lured his Sogdian advisor into a trap and killed him. He stopped paying tribute and briefly besieged Emperor Yang of Sui in Shanxi.