Duke Huan of Qi (齊桓公, Qí Huán Gōng, died 643 BC) was the best-known ruler of the state of Qi in the Spring and Autumn Period of Chinese history. His personal name was Jiāng Xiǎobái (姜小白) and he was the brother of Duke Xiang. He had been the duke of Qi from 685 BC until his death. At the moment he took his throne, Duke Huan appointed Guan Zhong, a great politician, to be his Prime Minister. The outstanding Prime Minister started a reform which made his state the strongest at his time. After the reform had succeeded, Duke Huan made more effect outside his state. Under the slogan of ‘respecting the king and defending against the barbarian’, Duke Huan gained hegemony among the states. He helped states of Yan, Xing and Wei against the barbarian troops. He also called for some states to attack the state of Chu in order to ‘defend the honor of the king’.