خوب اگه انگلیش تون خوبه بخونین !
Historically, there have been archers' thumb rings made by the
Chinese, Manchus, Indians, Turks, and Persians. They were worn on the
thumb of the left hand to protect it from injury by the bowstring
after the discharge of the arrow. In China, they eventually became the
insignia of military rank, and were of jade or a glass imitation of
jade. The tridition spread across the far east, and thumb rings became
like a badge of status - the bigger and more ornate they were, the
more powerful a man you were.
لینک توضیح کاملش!