Liu Wuzhou (劉武周) (died 622?) was a rebel leader who rose against the rule of the Chinese dynasty Sui Dynasty late in the dynasty's history, and he took imperial style -- although it was not completely clear whether the title he took was khan or tianzi. He was initially only able to take control of modern northern Shanxi and parts of central Inner Mongolia, but after Li Yuan established Tang Dynasty at Chang'an as its Emperor Gaozu in 618, he, with support from Eastern Tujue, briefly captured Li Yuan's initial power base of Taiyuan in 619, posing a major threat to Li Yuan's rule. In 620, Li Yuan's son Li Shimin (the future Emperor Taizong) counterattacked, and not only recaptured Taiyuan but further captured Liu's power base Mayi (馬邑, in modern Shuozhou, Shanxi), forcing Liu to flee to Eastern Tujue. When Liu subsequently tried to flee back to Mayi, Eastern Tujue executed him.
Read more about Liu Wuzhou: Initial Establishment of Dingyang, Campaign Against Tang, Defeat and Death