A Chinese surgeon named Hua Tuo was born around 140 CE and became famous for his talents in compounding natural herbs into medicine. The most amazing of his creations was called mafeisan, a plant-based anesthetic. Administered as a drink, mafeisan would render a patient unconscious and numb enough to undergo serious surgery, such as resecting damaged intestines. The patient would awaken after 24 hours or so, and recover from the anesthetic in a few days. We don't know how accurate that is, since all accounts of Hua Tuo's work are from later, secondhand writing. Unfortunately, Hua Tuo fell out of favor with a warlord he had previously saved. The doctor's mafeisan recipe was lost when he was executed, and surgery in general fell out of favor in China.
Much later in Japan, surgeon Hanaoka Seishū was inspired by Hua Tuo and spent decades developing an anesthetic called tsūsensan. In 1804, he performed a mastectomy on a cancer patient which is credited as the first documented surgery using general anesthesia. He went on to perform hundreds of surgical operations using tsūsensan, and taught his methods to medical students. Read about the development of surgical anesthesia before ether and chloroform at Amusing Planet.
(Image credit: Nat Krause)