Early Chinese civilization originated around 4000 BCE in the Yellow River valley, where some of the earliest forms of agriculture developed. Over time, civilization expanded along China's major river systems, including the Yangtze River. During the Shang Dynasty from around 1700-1050 BCE, Chinese civilization advanced with developments in bronze metallurgy, the earliest forms of writing in the form of oracle bones, and a new social hierarchy. The subsequent Zhou Dynasty built upon these foundations and established feudalism as a new political system from 1050-256 BCE.