Early Chinese civilization was shaped by its geography of major rivers and mountain ranges. The Huang He and Chang Jiang rivers provided fertile land for farming, though only 10% of China's land was arable, with the rest being mountains or desert. The first centers of Chinese civilization emerged in the Huang He valley, including the Xia Dynasty, though little is known about this early period. The subsequent Shang Dynasty established the city of Anyang in northern China. The Zhou Dynasty then ruled for over 800 years, developing bureaucracy and the concept of "Mandate of Heaven" to justify their right to rule based on virtue. During this period, the Chinese developed new tools like iron plows and engaged in extensive trade of silk along