Ancient Chinese Archery Thumb Ring - King of Rui

Archery thumb rings, or 扳指 (bān zhǐ), have a long history in China. This ring was excavated from the tomb of the king of the State of Rui (from the Spring-Autumn Period, 771-476 BCE).

Modern reproductions of this style of ring still exists, for example in this Youtube video:

This model was created with only the attached photos as reference, I have never seen the actual item in real life. Therefore I don't know the actual dimension of the real thing. The model is sized to fit my thumb. The narrow part of the thumb hole is 20mm across.