4000 BCE: Cannabis was listed among"five grains" in China, and was farmed as a major food source and prized for the oils and buds.
2737 BCE: Earliest record of cannabis as a medicinal drug. Emperor Shen-Nung, who is considered to be the father of Chinese medicine recognized cannabis and its treatment properties.
1500 BCE: Earliest Written Reference to Medical Marijuana in Chinese Pharmacopeia.
2000-1000 BCE: Ayurvedic Medicine taught the use of cannabis and allowed for exploration of medical benefits. During this period, it was used to treat a variety of ailments such as epilepsy, rabies, anxiety, and bronchitis.
1550 BCE: Egyptian medical papyrus of medical knowledge notes that medical cannabis can treat inflammation.
900 BCE: The Assyrians employed the psychotropic effects of cannabis for recreational and medical purposes.
450-200 BCE: Physician Dioscorides prescribed cannabis for toothaches and earaches. Greek doctor Claudius Galen noted it was widely consumed throughout the empire. Women of the Roman elite also used cannabis to alleviate labor pains.
207 CE: Hua T'o, a Chinese surgeon, was the first recorded physician to describe cannabis as an analgesic. He used a mixture of cannabis and wine to anesthetize patients before surgery.
1000 CE: Arabic scholars al-Mayusi and al-Badri regard cannabis as an effective treatment for epilepsy.
1025 CE: The medieval Persian medical writer Avicenna publishes "Avicenna's Canon of Medicine," stating that cannabis is an effective treatment for gout, edema, infectious wounds, and severe headaches. His work was widely studied from the 13th to 19th centuries, having a lasting impact on Western medicine.
1300 CE: Arab traders bring cannabis from India to Eastern Africa, where it spreads inland. It is used to treat malaria, asthma, fever, and dysentery.
1839 CE: William O’Shaughnessy an Irish doctor introduced medicinal uses of cannabis to Western medicine. He concluded it had no negative medicinal effects, and the plant’s use in a pharmaceutical context would rapidly rise thereafter.
1900 CE: Medical cannabis was used to treat nausea, rheumatism, and labor pain. At this point in time, it is available in many over-the-counter medications.
1937 CE: The Marihuana Tax Act banned the use and sales of cannabis in the United States. New York mayor Fiorello LaGuardia disagrees with the legislature and appoints the New York Academy of Medicine to do a five-year study that finds cannabis safe, nonaddictive, and not necessary to criminalize. The American Medical Association also opposes the stamp tax due to the fact that doctors, pharmacists, and cultivators would pay the tax and that American patients would suffer.
1964 CE: The molecular structure of THC, an active component of cannabis, was discovered and synthesized by Israeli chemist Dr. Raphael Mechoulam.
1970 CE: Classified as Schedule 1 Drug. Cannabis became categorized as a Schedule 1 Drug in the U.S., which limited further research into the plant. It was listed as having "no accepted medical use."
1988 CE: The CBD1 and CBD2 cannabinoid receptors were discovered. Today, we know they are some of the most abundant neuroreceptors in the brain.
2000-2018 CE: 38 states as well as the nation's capital District of Columbia have legalized at least the medicinal use of cannabis. 24 states have also legalized cannabis for recreational use. The Canadian government subsidizes the purchase of cannabis by its veterans suffering from PTSD.