From ancient China to the pharaohs of Egypt, to the Greeks and Arabs, cannabis has been one of the most used and effective medicines in history.
In 1937 the Marijuana Tax Act came into force in the United States , which prohibited the sale of cannabis in that country, promoted by "drug czar" Harry J. Anslinger, the first head of the Federal Narcotics Office. Three years later Anslinger also took his crusade to Mexico, abruptly thwarting the world's first anti-prohibitionist attempt in the field of drugs, decreed by president Lázaro Cárdenas in the country south of the US border.
That law, and those that succeeded it, classified as a drug what had hitherto been one of the most used and effective medicines in history: cannabis, first in Asia, later in Europe and, finally, all over the world.
This world map, produced by Visual Capitalist and MedReleaf, illustrates some of the milestones in the history of medical cannabis, from ancient China to the isolation of THC in 1964. For example:
4000 BC: Village of Pan-p'o
Cannabis was considered one of the "five grains" in China, and was cultivated as one of its main crops.
2737 BC: Pen Ts'ao Ching
First record of cannabis as a medicinal substance. At that time, Emperor Sheng-Nung recognised its therapeutic properties for a hundred ailments, such as gout, rheumatism, and malaria.
2000-1400 BC: Scythians
Nomadic Indo-European peoples used cannabis in steam baths, and also burned cannabis seeds in burial rituals.
2000-1000 BC: Atharva Vedas
Cannabis was described as "source of happiness", "giver of joy" and "bringer of freedom" in these Hindu religious texts. At that time cannabis was smoked in daily devotional services and religious rituals.
2000-1000 BC: Ayurvedic Medicine
The religious use of cannabis led to exploration of its medical benefits. During this time it was used to treat a variety of diseases, such as epilepsy, rabies, anxiety and bronchitis.
1500 BC: Ebers Papyrus
This Egyptian medical papyrus noted that cannabis can be used to treat inflammation.
1213 BC: Ramses II
Cannabis pollen was found in the mummy of Ramses II, the pharaoh who was mummified after his death in 1213 BC.
900 BC: Assyrians
They exploited the psychotropic effects of cannabis for both medical and recreational uses.
450-200 BC: Greco-Roman period
The physician Dioscorides prescribed cannabis for earaches and toothaches. Greek physician Galen stated that its use was common throughout the Empire. Roman noble-class women also used cannabis to relieve labour pains.
207 AD: Hua T'o
The first medical record describing cannabis as a pain reliever. A mixture of cannabis and wine was used to anesthetise patients before an operation.
1000 AD: Treatment of epilepsy
Arab scholars al-Mayus and al-Badri recommended cannabis as an effective treatment for epilepsy.
1025 AD: Avicenna
The Persian medieval doctor published his Canon of Medicine, in which he stated that cannabis is an effective treatment for gout, oedema, infectious wounds and migraines. His work was widely studied between the 13th and 19th centuries, having a major impact on western medicine.
1300 AD: Arab merchants
Arab traders brought cannabis from India and East Africa, where it was used as a remedy for malaria, asthma, fever, and dysentery.
1500: Spanish conquistadors
The Spanish took cannabis to the Americas, where it was put to more practical uses, such as to make rope and clothing. Years later, however, it began to be used as a psychoactive and medicinal drug.
Napoleon brought cannabis back to France from Egypt, and promoted research into it and its sedative qualities as a remedy for pain. At that time cannabis was used to treat tumours, cough, and jaundice.
1839: William O'Shaughnessy
This Irish doctor introduced therapeutic uses of cannabis into western medicine. He concluded that it does not have negative side effects, promoting the use of the plant in medical contexts.
1900: Medical cannabis
Medical cannabis was used to treat nausea, rheumatism, and labour pain. At this time medicines such as "Cure your cough in one day" were being sold.
1914: Harrison Act
The use of the drug was declared a crime in the United States, under the Harrison Narcotics Act of 1914.
1937: Marijuana Tax Act
This law prohibited the use and sales of cannabis in the United States.
1964: Discovery of THC
The molecular structure of THC, one of the active components of cannabis, was discovered and synthesized by the Israeli chemist Raphael Mechoulam.
1970: Classified on Schedule 1
Cannabis was classed on the US Drug Schedule 1, limiting research with the plant. It was listed with the observation "medical use not accepted".
1988: CBD receptors discovered
The cannabionoid receptors CB1 and CB2 are discovered. Today, we know that they are some of the most abundant neuroreceptors in the brain.
2000-2018: Legalisation of medical cannabis
The governments of Canada and some US states begin to legalise cannabis for medical uses, grown by licensed producers. The legalisation of recreational use spreads.