A unit of tension in ancient bows and arrows.

The unit of string tension of ancient bows and arrows is stone.

Stone is a unit of weight, and the standards of different dynasties are different. Usually it is based on the weight that a person can bear, that is, a "load". Modern is generally 94.4 kilograms.

If stone is used to calculate the bow force, it is to put the bow flat and hang heavy objects on the bowstring. See how many stones can fill the bow, then the bow force is how many stones. However, the stone used for the bow is only 30 kilograms, and generally a bow with more than 3 stones is considered a strong bow.