Speaking of hashish.

The name "assassin" is commonly believed to be a mutation of the Arabic hashshshin (???????), which allegedly derives from the drug hashish that was said to be used by the group before going into battle. However, there are those who dispute this etymology, arguing that it originates from Marco Polo's account of his visit to Alamut in 1273, in which he describes a drug whose effects are more like those of alcohol than of hashish. However, alcohol is not likely to have been the drug described, being totally prohibited by the Muslim faith. It is suggested by some writers that assassin simply means "followers of Al-Hassan" (or Hassan-i-Sabah, the Sheikh of Alamut)). Others suggest that since hashish-eaters were generally ostracized in the Middle Ages, the word "Hashshashin" had become a common synonym for "outlaws." So the attribution of Hassan's Ismaili sect with this term is not necessarily a clue for drug use. Some common accounts of their connection with hashish are that these "assassins" would take hashish before missions in order to calm themselves; others say that it helped to boost their strength, and turned them into madmen in battle. Yet other accounts state it was used in their initiation rites in order to show the neophyte the sensual pleasures awaiting him in the afterlife. The connection between their mysticism and that drug is not something subject to reliable or consistent historical accounts; this is not surprising given their secrecy and infamy.

The word Hashish (of probable Arabic origin) refers to resin collected from cannabis flowers. This could be the true drug of the Assassins as described by Marco Polo.