Actually, there are sources that say that the term is derived from Hassani'in because the name of their leader was Hassan.
Others say that it was Asasi'in. Asas can be used to describe 'the base of a structure' or 'the beginning or source of something'. Asasi'in could mean a lot of things. It could be 'those who were there in the beginning' or 'those who use or live by the old ways' or 'those who started (e.g, a trend)'.
To me, the English translation for it would be The Old School...
These theories are not nearly as cool as the other one though. :)
It is said that they also called them Hashashin, in a derrogatory way, (for arabs this term is a bit like the word junkie in English), because they were rumoured to smoke and drink and maybe use other drugs. Not in their missions though, but as part of an initiation ceremony or even an indoctrination period. Although, this contradicts the belief that they were all Muslim and were doing those killings in the knowledge that they were securing a place in Paradise.
Perhaps their enemies spread these rumours...?
Anyway, most accounts i've read say that their missions were usually suicidal. Which means that they were similar to present day Fedaeyin.
Naturally, European and Arab accounts are somewhat conflictive, so i don't think anyone knows what the deal with these people really was, other than, regardless of whether they were high, brainwashed, fervent believers or all of the above, they were very effective.
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