Cannabis was known to the Assyrians, who discovered its psychoactive properties through the Aryans. Used in religious ceremonies, they called it qunubu ("way to produce smoke"), a probable origin of the modern word cannabis.
The Aryans introduced cannabis to the following tribes;
Shamans a.k.a. Kapnobatai ("those who walk on smoke/clouds") burned cannabis flowers to induce trance.
The classical Greek historian Herodotus reported that the inhabitants of Scythia would often inhale the vapors of hemp-seed smoke, both as ritual and for their own pleasurable recreation.
Barber, Elizabeth Wayland. (1992). Prehistoric Textiles: The Development of Cloth in the Neolithic and Bronze Ages with Special Reference to the Aegean. Princeton University Press. p. 36.
People all across the middle latitudes of Europe and Asia – and that would include the early Indo-Europeans (IE's) – knew and were using hemp since 5000 B.C. So when IE groups started borrowing a new word four millennia later, it had to have been for a new use: drugs. The old northern varieties of hemp did not contain the narcotic THC; and the 2nd millennium was probably the first time that enough people were travelling back and forth between Iran (where it grew) and eastern Europe that they could spread a habit, along with its source, the THC-bearing hemp. And the early 1st-millennium B.C. is just when we begin to find evidence for pot-smoking in the new zone.
Barber's well-researched hypothesis involves two stages:
*ken- or *kan- name spread across Asia with the hemp plant, which was used for fiber and food. Then in the early Iron Age, an enlarged version of this very word, local to Iran and perhaps northern India, spread with the consumption for psychoactive purposes as THC was discovered.
