Cannabis is one of the earliest plants humans cultivated, and for most of that history it was unremarkable — a crop grown for fibre and seed alongside everything else. The history of cannabis is largely a history of an agricultural commodity that happened to have other properties.
Origins in Central Asia
Cannabis appears to have originated in Central Asia, with archaeological and genetic evidence pointing to the region around modern-day Mongolia and southern Siberia. Hemp fibre imprints on pottery from what is now China date back several thousand years, making it among the oldest documented fibre crops.
Early use was practical: fibre for rope, textiles and paper, and seeds for food and oil. Hemp seed was a staple grain in parts of ancient China before being displaced by higher-yielding cereals.
Medicine in China and India
Chinese medical texts record cannabis preparations from antiquity, attributed to the legendary figure Shen Nung and compiled over centuries into the pharmacopoeial tradition. Recorded applications included pain, digestive complaints, and conditions we would now describe differently.
In India the plant took on a different character. Cannabis appears in the Vedic tradition, and preparations — bhang, ganja and charas, distinguished by which part of the plant was used and how — were incorporated into both medical practice and religious observance. Ayurvedic medicine records a range of applications, and the association with Shiva placed cannabis inside religious life rather than alongside it.
That integration is the reason cannabis use in South Asia has a continuity that Western use does not. It was never entirely separated from ritual and medicine into a purely recreational category. More on that in cannabis in culture, ritual and creativity.
Westward Through the Middle East
Cannabis spread west through Persia and the Arab world, where it appears in medical texts as a treatment for pain, inflammation and epilepsy. Islamic scholars documented its properties in detail, and it was through Arabic medical literature that a good deal of this knowledge later reached Europe.
Herodotus described Scythian funerary practices involving cannabis smoke as early as the fifth century BCE — one of the oldest surviving accounts of inhalation for effect rather than for fibre or food.
Hemp in Europe and the Americas
In Europe, cannabis was grown overwhelmingly as hemp. Its fibre was the material of maritime power — rope, rigging, sailcloth — and its cultivation was in places compulsory. Several European states required landowners to grow hemp because naval capacity depended on it.
Colonists brought hemp to North America for the same reason. It was a required crop in parts of colonial America, and it remained an ordinary agricultural commodity into the twentieth century. The psychoactive properties of the plant were largely irrelevant to its cultivation in this context: fibre varieties were selected for stalk quality, not for resin.
Into Western Medicine
Cannabis entered Western medical practice substantially through William Brooke O’Shaughnessy, an Irish physician working in Calcutta in the 1830s. He studied Indian medical use, conducted his own trials, and published findings covering rheumatism, tetanus, cholera and convulsions — including a widely noted case of infantile convulsions.
His work brought cannabis into British and then American pharmacies. By the late nineteenth century it was a standard preparation, listed in the United States Pharmacopeia and sold by major manufacturers as tinctures and extracts.
Its medical decline began before any legal restriction. Injectable opiates and later aspirin offered more predictable dosing — cannabis preparations varied enormously in strength, which is the same problem potency testing exists to solve today.
Prohibition
The twentieth century reversed everything. International drug control treaties, national prohibitions, and in the United States the 1937 Marihuana Tax Act removed cannabis from ordinary commerce and then from medicine. It was dropped from the United States Pharmacopeia in 1942 and placed in Schedule I of the Controlled Substances Act in 1970.
The full account of that reversal, including the legislative history, is in from the Marihuana Tax Act to OMMA.
Prohibition did not end cultivation. It moved it — into clandestine production, selected increasingly for potency and concealability rather than for fibre or seed. Much of what defines modern cannabis genetics is downstream of decisions made by growers operating illegally. See cannabis genetics.
The Modern Reversal
Reform began at the margins. California’s medical programme in 1996 was the first modern breach in the United States. Uruguay legalised adult use nationally in 2013, Canada in 2018, and a majority of US states now permit medical or adult use in some form.
Hemp separated back out along the way. The 2018 Farm Bill removed cannabis containing no more than 0.3% delta-9 THC from federal control, restoring — in legal terms — the distinction between fibre and drug crops that had existed agriculturally for most of the plant’s history.
The global picture is set out in where cannabis is legal around the world.
What the History Actually Shows
Two things worth taking from five thousand years.
The prohibition era was an interruption, not the norm. Cannabis was an ordinary crop and an ordinary medicine for most of recorded history, and the twentieth century was the exception.
And the recurring practical problem has always been the same. Preparations varied unpredictably in strength, which limited their medical usefulness in the nineteenth century exactly as it would today. What has changed is not the plant — it is that we can now measure what is in it. That capability is the actual dividing line between historical use and modern regulated use, and it is what cannabis lab testing provides.