Ji Youyu, a descendant of King Xie of Zhou, fled to Xirong after King Xie of Zhou was killed by Wen Gong.
In 626 BC, Yu Yu, the most powerful Burmese leader in Xirong, sent him to the State of Qin.
In 625 BC, it was put back to Mianzhu after being detained by Qin for nearly a year. Then, Yu Yu and Mianzhu were not harmonious. At Mu Gong's secret invitation, Yu Yu, who was disheartened, defected to the State of Qin, and was treated with excessive courtesy and attention.
In 624 BC, Qin attacked with Yu, and successively captured twelve Rong countries, including Mianzhu Rong, Kunrong, ZhaiRong and Yiqu, and conquered XiRong for thousands of miles. The Emperor of Zhou sent messengers with golden drums to congratulate him.
On the issue of digging Yu Yu, Qin Mugong mainly started from two aspects. One is to make the kings of Xirong and Mian lose their morality and ambition. The effective way is to make them like to enjoy themselves with honey traps. Once they learn to enjoy themselves, they will not listen to advice. Secondly, in order to destroy the mutual trust between Wang Mian and Yu Yu, it is necessary to alienate their relationship by deviant behavior. The deviant use this time is to stay for a long time on the surface, which is good for them. Privately, it is natural to spread some gossip, giving people a feeling of liking the new and hating the old, which makes Rong Wang and Yu Junchen very unhappy.
Qin Mugong took great pains to dig Yu Yu out of the enemy's hands, and did not disappoint Mu Gong. Yu Yu, who is familiar with the situation in Xirong, gave Qin Mugong the strategy of attacking Rongrong: catching thieves and capturing the king, and attacking Rongrong with peace; Strong enough to destroy weak fears, overlooking the wind; Acquaintances open their eyes and know each other; Soldiers are expensive and fast, and they attack far away; Caught off guard, chasing after victory; Solve it completely, leaving no future trouble. Under the leadership and participation of Yu Yu, it took Qin Jun less than a year to incorporate the territory of the twelve countries in Xirong into its territory, which shocked the governors of the Central Plains.
In the history of Qin, Yu Yu is definitely an epoch-making figure. When the state of Qin had no choice but to go eastward, he put forward the strategy of going westward and put it into practice. He not only put forward the concept of "benevolence and righteousness" before the sage Confucius and Mencius, but also helped Qin Mugong rank among the five tyrants in the Spring and Autumn Period. This not only improved Qin's influence and position among the vassals, but also gave A Qin a broader strategic depth and development space, laying a solid foundation for Qin's reunification of the whole country after 400 years.
Yu Yu's descendants took his name as their surname, which was called Yu's and Yu's.