The Form That Held Up
Resin, From Harvest to Physician
In the late nineteenth century and into the twentieth, most of the charas sold in British India came from a single distant place. The Indian Hemp Drugs Commission of 1893–94 called it practically a foreign article. A little came from Nepal and Gwalior, and some from elsewhere in Central Asia by routes along the Afghan frontier, but the bulk arrived from Yarkand, in Chinese Turkistan, through the Himalayan passes. Traders brought it down into the Punjab, where Hoshiarpur and Amritsar were named as centers of the business. By the time it changed hands there, the plant had been harvested, and its resin had been worked, packed in hide, and carried through the mountains.
Every stage of that journey added time, and time was what the drug could least afford. Much of the interval between harvest and sale was spent in storage, first in the rawhide bags in which the resin was made and later in the stocks of those who carried and sold it. Heat and moisture were known to hasten its decay. The distance between harvest and use was measured in months and in miles, and the drug did not wait unchanged through either.
Those who handled these drugs for a living knew that some kept better than others. Charas was reckoned to last longer than ganja, the dried and pressed flowering tops. Ganja nonetheless stayed in trade throughout the period, sold on the plains while resin came down from the mountains.
Behind that difference lies a practical question the evidence answers only in pieces. For cannabis harvested in one place and one season to keep its strength until it reached the person who would administer it or take it, something had to go right at every stage in between. The first part of the answer lay in the ground where the plant grew.
Where Quality Began
Writers on the Indian hemp drugs tied the quality of these drugs closely to where the plant was grown. Surveying the cannabis drugs of India in 1957, I. C. and R. N. Chopra noted that the plant's narcotic properties became much more pronounced in Kashmir and Ladakh, while plants cultivated on the plains generally did not secrete the resin that makes charas. Among the resins, origin went a long way toward deciding grade. The highest yield and best quality came from plants grown at Yarkand. Charas collected on the plateaus of Central Asia and in the southern Himalayas of Nepal was described as poor in both yield and quality, and a resin smuggled from Gardez in Afghanistan, known as Garda charas, was regarded as inferior.
These are distinctions of place more than of season. The sources say little about how one year's crop at Yarkand differed from the next, and that silence is better left alone than filled with guesses about weather or harvest timing. What they do show is that the same drug could arrive in very different qualities, and that the differences observers wrote down were differences of origin.
The Chopras also describe how Yarkand charas was made. Dried female flower heads were crushed by hand and sieved to a powder with the consistency of sand or sawdust, which was then stored in rawhide bags and later worked into a solid mass. A modern reader may infer that gathering resin from many plants into one mass evened out some of the differences between individual plants. Nothing in the Chopras' account suggests that anyone sieved charas for that reason, and the idea belongs to present-day interpretation.
Years in Storage
On how long these drugs kept, the evidence is unusually specific. The excise authorities of the Indian plains found that ganja retained most of its activity for one year, began to lose potency gradually during the second, and became quite useless and unsaleable by the end of it. The prevailing opinion on charas, which was always imported, held that it was very potent in its first year and declined steadily until the fourth, when it had become practically inert. The same survey adds that charas deteriorated rapidly when exposed to heat and moisture.
Two things stand out. Resin did keep longer, roughly twice as long on these estimates, and neither form kept indefinitely.
Some of that time passed before charas ever left Yarkand. There, according to the Chopras, the sieved powder was stored in rawhide bags for four or five months through the winter. When the hot weather came it was set briefly in the sun until the resin melted, returned to hide bags, and after a few days kneaded with wooden rods until oil appeared on its surface. Only then was it moved into new hide bags. The resin had therefore spent four or five months in storage, and some further days of working, before it was considered ready for distribution. How long it waited after that is not recorded.
Twentieth-century laboratory work pointed in the same direction. Bioassays at Eli Lilly, reported in the 1957 survey, found that dry cannabis samples lost activity at about one percent a month over five years, and that sealed containers did not preserve them appreciably longer. Present-day chemistry adds explanations none of these observers had. THC oxidizes to cannabinol steadily enough that the ratio between the two has been used to estimate the age of stored samples. It is also a fair inference that a dense block of resin, with less surface open to the air than loose plant matter, would change more slowly, though no excise officer measured anything of the kind. Density did not stop the loss, however. A recent study of resin held under forensic storage conditions found steep declines in THC within two years.
Through the Passes
The trade that brought Yarkand charas south ran in both directions. Witnesses before the Hemp Drugs Commission described traders who took merchandise north to Ladakh and Yarkand and came back with charas, and the Commission's report noted that the Yarkand trader carried the products of the Punjab home to his own country or to Kashmir.
The sources do not say why this long-distance trade carried resin and not flowering tops. They do supply one plain fact. Yarkand was where the best charas was made. A modern reader may add that a dense resin in hide bags would have been easier to carry over high passes than the bulk of flower needed to match it. That may be part of the explanation, but it is a present-day reading of logistics and not a reason anyone at the time is recorded as giving. A 1953 account of the charas traffic describes a special warehouse at Leh where charas was deposited and from which it was distributed, a further stop before it moved on toward the plains.
Only a small part of the wider hemp-drug trade served medicine. Estimating habitual use across British India for 1939–40, the Chopras treated nearly all the hemp drugs issued by excise authorities as consumed for euphoric purposes and judged the amount used medicinally and quasi-medicinally to be small. Whatever charas reached a physician presumably came by the same roads as the rest of the trade.
In the 1930s Chinese authorities moved to prohibit the cultivation and export of charas at Yarkand, and by the Chopras' account India prohibited imports at around the same time. Charas went on arriving as contraband across the northwestern frontier, and that traffic left some of the clearest evidence of how badly resin could fare.
Where Resin Fell Short
Several of the sources that describe charas keeping longer also describe it failing. Heat and moisture could ruin it quickly, and stocks that sat too long lost their worth. When preventive measures along the frontier left smugglers holding charas in the Khyber and Kohat passes, the 1953 account reported that most of those stocks deteriorated with the lapse of time.
Quality could also be lowered on purpose. The same account reported that illicit charas was usually adulterated with foreign matter to the extent of about twenty to twenty-five percent. Tobacco and catechu were frequent additions, and charas was also mixed with bhang made into a paste. Neither the 1953 account nor the Chopras describe a ready way for a buyer to tell how much of a lump was resin.
Even resin sent in good faith could arrive diminished. In the London edition of his memoir, published in 1843, O'Shaughnessy added a closing note that numerous cases had come to his knowledge in which churrus, the resin prepared in India for smoking, had been used with little effect. One of them involved experiments by Dr. Pereira with churrus that O'Shaughnessy had sent him personally. Age and adulteration, he wrote, had probably both played a part. The fuller story of his work is told elsewhere. Here it is enough that the explanation was a probable one, offered after the failure, and that even the man who had sent the resin could not say for certain what had happened to it.
Buyers in India faced the same uncertainty. The surviving accounts mention no mark or document that traveled with a lump of charas to show when it had been sieved, how long it had waited at Yarkand or Leh, or what had been worked into it. Resin's advantage over flower was genuine, yet it could be exhausted entirely before the charas reached anyone who meant to give it as medicine.
What Was Left
The old accounts measure these drugs in years of usefulness and differences of origin. They say almost nothing about what the drugs contained, which no one at the time could determine. Within those limits, they record something later chemistry has confirmed. By the time it reached a physician, the drug was no longer simply the plant as it had been harvested. It was what the months of storage and the long road had made of it.
Resin slowed that loss of strength without preventing it. Origin decided the quality a batch started with. Everything that followed, from the hide bags at Yarkand to the warehouse at Leh to whatever hands it passed through on the plains, decided how much of that quality remained.
One modern counterpart is worth naming, though it stands apart from the historical account. The living plant makes its principal cannabinoid as THCA, an acidic form that converts to THC when heated and is sensitive to time in storage. For raw THCA preparations, the old question of what survives between harvest and use has not gone away. What has changed is that the loss can now be measured.
The traders at Yarkand and the excise officers of the plains never described their work in those terms. What they left is a plain account of a drug changing on its way to the people who would take it, and of resin as the form that changed more slowly than flower without ever standing still.
References & Citations
Chopra, I. C., & Chopra, R. N., Bulletin on Narcotics, 1957 — survey of the production, trade, use, and keeping qualities of cannabis drugs in India.
Informs: Documents regional differences in charas quality, the Yarkand preparation method, reported keeping times for ganja and charas, deterioration with heat and moisture, and the relatively small medicinal share of cannabis-drug consumption.
Indian Hemp Drugs Commission, Report of the Indian Hemp Drugs Commission, 1893–94, 1894 — official inquiry into cannabis production, commerce, administration, and use in British India.
Informs: Provides the historical basis for charas as a largely imported commodity, its movement from Yarkand through Himalayan trade routes, and the role of Punjab centers such as Hoshiarpur and Amritsar in the trade.
United Nations, Bulletin on Narcotics, 1953 — “The Surprising Extinction of the Charas Traffic.”
Informs: Describes the later Yarkand charas trade, storage and distribution through Leh, adulteration of illicit supplies, and deterioration of stocks delayed along the northwestern frontier.
O’Shaughnessy, W. B., Provincial Medical and Surgical Journal, 1843 — “On the Preparations of the Indian Hemp, or Gunjah,” 5(123), 363–369.
Informs: Supplies O’Shaughnessy’s account of churrus producing little effect in numerous cases, including material he sent to Dr. Pereira, and his cautious attribution of the poor activity to probable age and adulteration.
Fettoukh, N., Fadil, M., Stambouli, H., El Bouri, A., Bouyoun, T., Annemer, S., Boukhaled, A., & Farah, A., Scientific Reports, 2025 — “Chemometric and Predictive Modeling of Long Term Cannabinoid Transformation in Stored Cannabis sativa Resin,” 15, 33827.
Informs: Shows substantial changes in cannabinoid composition during long-term resin storage, including marked THC decline, supporting the article’s restrained modern comparison between historical loss of activity and measurable cannabinoid change over time.