In the spring of the 10th year of the reign of Duke Ding of Lu state (500 BC), Duke Jing of Qi state invited Duke Ding of Lu state to Jiagu, which on the border of Qi state and Lu state, to hold an alliance meeting. Duke Jing intended to make Lu state a vassal state of Qi. At that time, Confucius was the acting prime minister of Lu state, and the officer of propriety of the ceremony. Because Confucius deployed soldiers in advance to be on guard, the plot of Duke Jing to kidnap Duke Ding and the officials of Lu state by force failed. However, Duke Jing also arranged assassins disguised as music performer and dancer. After the two sides toasted each other, performers of Qi state played the music of barbarians. Confucius said that the music of barbarians could not be played when two dukes meet. As a result, Duke Jing was forced to cancel the performance. Then Duke Jing ordered court musical dances to be performed. Confucius accused the dancer of plotting to confuse superiors, so Duke Jing was forced to punish the dancer again. Therefore, the plots of Qi had all failed, and Lu state achieved a victory in diplomacy.