According to a report by the Canadian Press, the 789 grams of dried cannabis was buried alongside a light-haired, blue-eyed Caucasian man, likely a shaman of the Gushi culture, near Turpan in northwestern China.
Researchers said that the cache of cannabis was clearly cultivated for psychoactive purposes, rather than as fibre for clothing or as food.
The extremely dry conditions and alkaline soil acted as preservatives, allowing a team of scientists to carefully analyze the stash, which still looked green though it had lost its distinctive odour.
To our knowledge, these investigations provide the oldest documentation of cannabis as a pharmacologically active agent, said American neurologist Dr. Ethan B. Russo, lead author of the research paper.
Remnants of cannabis have been found in ancient Egypt and other sites, and the substance has been referred to by authors such as the Greek historian Herodotus.
But, the tomb stash is the oldest so far that could be thoroughly tested for its properties.
The 18 researchers, most of them based in China, subjected the cannabis to a battery of tests, including carbon dating and genetic analysis. Scientists also tried to germinate 100 of the seeds found in the cache, without success.
The marijuana was found to have a relatively high content of THC, the main active ingredient in cannabis, but the sample was too old to determine a precise percentage.
Researchers also could not determine whether the cannabis was smoked or ingested, as there were no pipes or other clues in the tomb of the shaman, who was about 45 years old.
The large cache was contained in a leather basket and in a wooden bowl, and was likely meant to be used by the shaman in the afterlife.
This materially is unequivocally cannabis, and no material has previously had this degree of analysis possible, said Russo.
It was common practice in burials to provide materials needed for the afterlife. No hemp or seeds were provided for fabric or food. Rather, cannabis as medicine or for visionary purposes was supplied,he added.
According to Russo, the substance has been found in two of the 500 Gushi tombs excavated so far in northwestern China, indicating that cannabis was either restricted for use by a few individuals or was administered as a medicine to others through shamans.
It certainly does indicate that cannabis has been used by man for a variety of purposes for thousands of years, he said.