History of Cannabis: From Ancient Asia to Modern Legalization

The history of cannabis stretches back at least 2,500 years, from ritual use in Central Asia and centuries as a mainstream medicine, through a 20th century in which it became illegal almost everywhere on Earth, to today's growing wave of legalization. Long before anyone argued about legalization, the plant was already woven into medicine, textiles, religion and trade across three continents — and how it went from an ordinary farm crop to a globally banned drug and back toward legal acceptance says as much about human politics as it does about the plant itself. Written for readers who are new to cannabis and want the full picture rather than a single decade of it, this guide walks through that history in order: where cannabis began, how it spread, why it was prohibited almost everywhere in the 20th century, and how the legal tide has been turning since the 1990s.

Where Cannabis Began: Central and East Asia

Botanists trace Cannabis sativa's origins to Central Asia, in the region spanning modern-day Mongolia and northwest China, where the plant likely grew wild before humans began cultivating it. Early farmers had two reasons to grow it: the stem's tough fiber, useful for rope, cloth and paper, and the resinous female flowers, prized for their psychoactive and medicinal effects.

The clearest physical evidence of cannabis's ritual use comes from the Jirzankal Cemetery in the Pamir Mountains of western China. Wooden burners recovered from 2,500-year-old tombs there tested positive for cannabinoid residue with unusually high THC content, indicating the people buried there were deliberately selecting potent plants and burning them, likely as part of funerary ritual, around 500 BCE. The findings, published in a 2019 study in Science Advances, pushed back the confirmed timeline for intentional cannabis smoking by centuries.

An Ancient Medicine and an Ancient Crop

Cannabis shows up early in the historical record as medicine, not just ritual. Chinese medical tradition credits the legendary Emperor Shen Nung with cataloguing cannabis as a treatment for pain, gout and malaria as far back as 2700 BCE, though the story is passed down through later texts rather than contemporary written records. In India, cannabis is named among the sacred plants in the Atharvaveda, a Hindu religious text compiled roughly 3,000 years ago, and the plant became — and remains — part of Ayurvedic medicine and religious practice, consumed as bhang, a drink made from ground cannabis leaves, particularly during festivals like Holi.

Hemp fiber, meanwhile, was quietly doing just as much work as the drug. Chinese papermakers used hemp fiber in some of the earliest paper ever produced, and hemp rope and cloth became staples of shipping and agriculture across Asia and, later, Europe — a use so essential that several American colonies once required farmers to grow it.

The Plant Travels: Trade Routes to the Middle East, Africa and Europe

Cannabis moved wherever people and goods moved. It spread west into the Middle East and North Africa along the same trade routes that carried silk and spices, where hashish — a concentrated form of cannabis resin — became a well-documented part of urban life by the medieval period, referenced in period writings from cities like Cairo. It spread south into sub-Saharan Africa through trade and migration, where it was absorbed into local medicine and, later, agricultural economies. It reached Europe more slowly and mainly as hemp for rope and sailcloth rather than as a drug — European interest in cannabis as medicine didn't take off until the 19th century.

That shift is largely credited to William O'Shaughnessy, an Irish physician working in colonial India in the 1830s and 1840s, who studied cannabis's use in local medicine and introduced cannabis extracts to Western doctors. Within a few decades, cannabis tinctures were a standard part of Western medicine cabinets, prescribed for everything from muscle spasms to migraines.

Cannabis Arrives in the Americas

Hemp arrived in the Americas with European colonization in the 16th and 17th centuries, grown for rope and textiles rather than its psychoactive effects. Cannabis as a smoked drug came later and along a different route: it entered the United States largely through Caribbean and Mexican immigration in the late 19th and early 20th centuries, and separately through the Western medicine tradition that had already normalized cannabis tinctures in American pharmacies.

By the mid-1800s, cannabis extract was listed in the United States Pharmacopeia, the official reference for approved medicines, and stayed there until 1942 — cannabis was, for close to a century, an ordinary part of American medicine, not a banned substance.

From Medicine Cabinet to Contraband

That changed fast in the 20th century. Anti-immigrant sentiment following the Mexican Revolution fed a wave of local and state bans on cannabis in the U.S. during the 1910s and 1920s, often tied explicitly to fears about Mexican immigrants rather than the drug itself. Harry Anslinger, the first commissioner of the U.S. Federal Bureau of Narcotics, spent the 1930s campaigning hard against cannabis, and in 1937 the Marihuana Tax Act effectively criminalized it nationwide by taxing it into practical unavailability.

Public opinion followed the law: sensational press coverage and propaganda films of the era, most infamously the 1936 film "Reefer Madness," cast cannabis as a violent, corrupting drug rather than the medicine it had been a generation earlier. Cannabis was dropped from the U.S. Pharmacopeia in 1942, and in 1970 the Controlled Substances Act placed it in Schedule I — the U.S. Drug Enforcement Administration's most restrictive category, reserved for drugs deemed to have no currently accepted medical use, a classification the DEA maintains for cannabis at the federal level to this day.

That classification survived its own government's evidence to the contrary. A 1972 U.S. commission chaired by former Pennsylvania governor Raymond Shafer — convened by President Nixon himself — recommended decriminalizing personal cannabis possession after finding it posed far less risk than its legal status implied. Nixon rejected the recommendation outright, and Schedule I status has remained in place at the federal level ever since. Internationally, the 1961 United Nations Single Convention on Narcotic Drugs pushed similar prohibition across most of the world, and by the 1970s cannabis was illegal in some form in the vast majority of countries.

Key Dates at a Glance

• ~500 BCE — Ritual cannabis smoking documented at Jirzankal Cemetery, Pamir Mountains
• 1830s–1840s — William O'Shaughnessy introduces cannabis to Western medicine
• 1850–1942 — Cannabis extract listed in the United States Pharmacopeia
• 1937 — U.S. Marihuana Tax Act effectively criminalizes cannabis nationwide
• 1961 — UN Single Convention on Narcotic Drugs internationalizes prohibition
• 1970 — U.S. Controlled Substances Act places cannabis in Schedule I
• 1972 — Shafer Commission recommends decriminalizing personal possession; the Nixon administration rejects it
• 1996 — California becomes the first U.S. state to legalize medical cannabis
• 2013 — Uruguay becomes the first country to legalize recreational cannabis nationwide
• 2018 — Canada becomes the second country to legalize recreational cannabis nationwide

The Legalization Turn: 1990s to Today

The tide started turning in 1996, when California voters passed Proposition 215 and became the first U.S. state to legalize medical cannabis use, a shift that eventually made CBD-rich strains as easy to find as high-THC ones. Other states followed through the 2000s, and in 2012 Colorado and Washington became the first states to legalize recreational cannabis for adults, opening the era of state-licensed dispensaries.

Other countries moved on their own timelines. The Netherlands has tolerated cannabis sales through licensed "coffeeshops" since the 1970s without ever formally legalizing the drug — a policy of tolerance rather than legality. Uruguay went further in 2013, becoming the first country to fully legalize recreational cannabis nationwide, followed by Canada in 2018 under the Cannabis Act, which built a national legal market for adult use and home cultivation.

Today the global picture is a genuine patchwork: full legalization in a growing number of countries and U.S. states, medical-only access in many more, decriminalization — no legal sales, but no criminal penalty for personal possession — in others, and outright prohibition in a shrinking but still substantial share of the world.

Frequently Asked Questions

When was cannabis first used by humans?

The oldest confirmed evidence of cannabis use is chemical residue from wooden burners in 2,500-year-old tombs in the Pamir Mountains of western China, showing ritual cannabis smoking around 500 BCE. Cannabis cultivation for fiber likely predates this by thousands of years, though that evidence is harder to date precisely.

Why did cannabis become illegal?

In the United States, cannabis prohibition grew out of anti-immigrant sentiment in the 1910s–1920s and a deliberate federal campaign led by Harry Anslinger, culminating in the 1937 Marihuana Tax Act. Internationally, the 1961 UN Single Convention on Narcotic Drugs spread similar prohibition to most of the world by the 1970s.

Which country legalized cannabis first?

Uruguay was the first country to fully legalize recreational cannabis nationwide, in 2013. Canada followed in 2018, becoming the second. Several other countries have since decriminalized cannabis or legalized it for medical use without going as far as full recreational legalization.

Is cannabis legal everywhere now?

No. Legal status still varies enormously by country and, in the U.S., by state — ranging from full recreational legalization to medical-only access, decriminalization and outright prohibition. Always check your local laws before buying seeds or growing cannabis, since rules can differ even between neighboring regions.

The Bottom Line

Cannabis history didn't start with prohibition, and it isn't ending with the current wave of legalization either — it's a plant that has been medicine, fiber crop, ritual object and contraband, sometimes all within the same century. Understanding that arc explains a lot about why cannabis laws still look so different from place to place today.

If you want to see where that history has led, start with what cannabis actually is at a plant level, browse the strain library to see the genetics a century of prohibition and breeding actually produced, or head to our seed bank comparisons when you're ready to buy.