are you serious? lol
ahem......
marijuana
opium
Angel trumpets
shrooms
tobacco
alcohol
all drugs used.... since way before midevil times... and recognized as, maybe not he word exatcly, but drugs.
as far as planeshift world. all it would take is one person to feel the effects. and they tell one person, then they tell one person, and so on and so on. and you say not to many poeple would go for it? people dont do drugs because its labeled a drug. people do drugs for the effects, the feelings, the alteration of reality at the most. because noone knows what "drugs" are, would they really not do a substance that makes them feel better? of couse they would, its called alcohol =)