Counting rods (筭) are small bars, typically 3–14 cm long, that were used by mathematicians for calculation in ancient East Asia. They are placed either horizontally or vertically to represent any integer or rational number.

The Warring States period was an era in ancient Chinese history characterized by warfare, bureaucratic and military reform, and political consolidation. It followed the Spring and Autumn period and concluded with the wars of conquest that saw the state of Qin annex all the other contender states by 221 BC and found the Qin dynasty, the first imperial dynasty in Chinese history.