 Around 650 BC, Yiqu had conquered most of its surrounding smaller tribes and began to expand eastwards, bringing it into direct conflict with the state of Qin.In 651 BC, one of the other larger Xirong tribes, Mianzhu, recruited a Jin man in exile named You Yu (由余) as the ambassador to Qin in order to improved the strained diplomatic relationship.However, You Yu secretly defected and gave counsel to Duke Mu of Qin regarding ways to defeat the Xirong.