Early Chinese civilization began around 2070 BC in the Huang He (Yellow River) valley, with important dynasties including the Xia, Shang, and Zhou dynasties. Government was organized under a series of dynastic rulers, with early kings also serving religious roles. Farming, especially of rice and wheat, and trade along the Silk Road were important economic activities. Writing developed around 1500 BC using oracle bones, and architecture featured symmetrical designs with column support. Chinese art, science, and technology advanced over this period, with inventions including paper, gunpowder, and the magnetic compass.