King Zhaoxiang of Qin
In 293 BC, East Zhou decided to ally itself with the states of Han and Wei, and sent troops to help attacking Qin. However, the combined forces of this alliance was destroyed at Yique by the young Qin general Bai Qi, with 240,000 men killed and their commander Gongsun Xi (公孫喜) captured and executed. After this loss, the East Zhou was unable to actively participate in future interstate struggles in any significant fashion.
In 256 BC, Duke Wu of West Zhou (西周武公) allied with other states to stop the Qin offensive on the Han city of Yangcheng. In retaliation, King Zhaoxiang of Qin sent general Jiu to invade West Zhou, successfully breaking into Wangcheng. The Duke Wu was taken to Xianyang to beg for mercy, conceding all his lands. Both King Nan and Duke Wu would die later that year, and the subsequent Duke of West Zhou, Duke Wen (西周文公), was exiled to Danhuju (憚狐聚). Because the Zhou royal court had fallen from power and King Nan had died without a successor, the Eastern Zhou Dynasty collapsed, ending 879 years of Zhou monarchy. The remaining East Zhou state was also conquered by Qin chancellor Lü Buwei seven years later in 249 BC during the reign of King Zhaoxiang's grandson King Zhuangxiang, after Duke Jing of East Zhou attempted to form an anti-Qin alliance with other states.
King Zhaoxiang of Qin
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. Using You Yu's advice, Duke Mu sent women and musicians to the king Mianzhu, distracting him from domestic affairs. In 623 BC, Duke Wu led a well-prepared Qin army, invaded and conquered Mianzhu along with over 20 smaller Rong and Di states. Yiqu was among those defeated and forced to claim fealty to Qin's military prowess. For his dominance in the western region, Duke Mu received a golden drum from King Xiang of Zhou as commendation, and was later regarded as one of the Five Hegemons. However, after Duke Mu died, the subsequent Qin rulers were not as competent as their forebear. Being the most sinicized of all Xirong tribes, Yiqu spent the next two centuries slowly building up its strength. In 430 BC, Yiqu invaded Qin territory, forcing Duke Zao of Qin to abandon lands north of lower Wei River. The following three decades were the pinnacle of Yiqu power, with its territory doubling to almost . At this point, Yiqu had become a major threat to Qin, who had to solely focus on dealing with this north-western neighbour and thus became marginalised by other major Central Plain vassals states to the east.