nd Chengzhou. Over time, this decentralized system became strained as the familial relationships between the Zhou kings and the regional dynasties thinned over the generations. Peripheral territories developed local power and prestige on par with that of the Zhou. The conflicts with nomadic tribes from the north and the northwest, variously known as the Xianyun, Guifang, or various "Rong" tribes, such as the Xirong, Shanrong or Quanrong, intensified towards the end of the Western Zhou period. These tribes are recorded as harassing Zhou territory, but at the time the Zhou were expanding northwards, encroaching on their traditional lands—especially the Wei River valley. Archaeologically, the Zhou expanded to the north and the northwest at the expense of the Siwa culture. When King You demoted and exiled his Qiang queen in favor of the commoner Bao Si, the disgraced queen's father the Marquis of Shen joined with Zeng and the Quanrong. The Quanrong put an end to the Western Zhou in 771 BC, sacking the Zhou capital at Haojing and killing the last Western Zhou king You. With King You dead, a conclave of nobles met at Shen and declared the Marquis's grandson King Ping. The capital was moved eastward to Wangcheng, marking the beginning of the Eastern Zhou pe