In 1986, scientists independently identified the structure of a nerve cell receptor, now called CB1, which responded to Δ9-THC and was the first cannabinoid receptor to be documented. A few years later, researchers identified an additional cannabinoid receptor, CB2. Cannabis was one of the first plants to have been used as a medicine, for religious ceremonies and recreationally, the first accounts of its use for these purposes stretching back 5000 years.

Important milestones in the pharmacohistory of individual cannabinoids have been their discovery at the end of the 19th century, their pharmacological characterization which began in the 1940s, the structural elucidation and synthesis of Δ9-THC and CBD in the 1960s and the discovery of the system of cannabinoid receptors and endogenous ligands for these receptors now generally referred to as the endocannabinoid system.