During the Shang dynasty (1600 -1046 BC) and Zhou dynasty (1046 – 256 BC), bronze coins of relatively standard form and weight were introduced for bartering. The early bronze coins took the shape of shovels when trade developed further in the late Spring and Autumn Period（770 – 476 BC), and gradually became smaller in the later period.
Bronze coins with a round hole in the middle appeared during the late Warring State Period in China. In 210 BC, Qin Shi Huang (秦始皇), founder of the Qin dynasty united the nation and uniformed the currency. He altered the round hole at the centre of bronze coins into a square. The round coin and its square hole are considered to reflect the ancient theory that “heaven is round and earth square”. This style formed the basis for the standard form of Chinese bronze coins for the following 2000 years. Further reform came in 118 BC, when Emperor Wudi created the Wuzhu coin (五铢), which was widely used for the next 700 years. Early coins were valued on their weight, and a Wu Zhu coin weighed around 3.5 grams or the equivalent of 100 grains of millet.
