People discovered the plant's versatility, using it as a medicine, food source, raw fiber material for ropes and textiles and even exploiting its mind-bending properties.
However, while in western Eurasia humans made a regular use of the herb down the millennia, there are relatively scarce archaeological records for an early use of cannabis achene in East Asia.
Things changed at the dawn of the Bronze Age, about 5000 years ago. A marked increase in records shows the use of cannabis intensified in East Asia at that time.
Such increase "might be associated with the establishment of a trans-Eurasian exchange-migration network through the steppe zone," the researchers said.
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The Yamnaya and their neighbors such as the Botai, who might have domesticated wild horses and were able to travel vast distances across the relatively flat steppe region, began a transcontinental trade network even stretching to the Hexi Corridor region. This route in Gansu province of China would become part of the Silk Road several millennia later.
"Cannabis's multiple usability might have made it an ideal candidate for being a 'cash crop before cash', a plant that is cultivated primarily for exchange purpose," Tengwen Long, a paleontologist at German Archaeological Institute and the Free University of Berlin, told Discovery News.
Carbonized achenes and signs of cannabis burning found at archaeological sites suggest the Yamnaya brought the practice of cannabis smoking with them as they spread across Eurasia, although they may have inhaled the smoke only during rituals.
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"However, the value of cannabis should not be overly emphasized, as in the Bronze Age the exchange certainly did not confine to this plant," Long said.
"Bronze objects, technologies, staple food crops such as millets, wheat, and barley, horses, and pandemic diseases were all possibly parts of the story," he added.
The researchers noted that more data, especially from the Eurasian steppe zone, is needed.
"There are a lot of unaddressed questions awaiting scientists to answer in terms of the long history of cannabis and the Bronze Age Eurasian connections," Long said.