When was ancient Chinese acupuncture first used?

Ancient Chinese acupuncture is believed to have originated around 2,500 years ago, with its earliest documented references found in texts such as the "Huangdi Neijing" (The Yellow Emperor's Classic of Internal Medicine), which dates back to the Han Dynasty (206 BCE – 220 CE). Archaeological findings suggest that practices resembling acupuncture may have existed even earlier, around 5000 to 3000 BCE, when stone tools were used for similar therapeutic purposes. Acupuncture has since evolved into a significant component of Traditional Chinese Medicine.