Maybe thats because they did not have gun powder yet.
In the account given by Marco Polo in "The Adventures [or Travels] of Marco Polo" it is told that "The Old Man kept at his court such boys of twelve years old as seemed to him destined to become courageous men. When the Old Man sent them into the garden in groups of four, ten or twenty, he gave them hashish to drink. They slept for three days, then they were carried sleeping into the garden where he had them awakened.
"When these young men woke, and found themselves in the garden with all these marvelous things, they truly believed themselves to be in paradise. And these damsels were always with them in songs and great entertainments; they; received everything they asked for, so that they would never have left that garden of their own will."
When the Old Man wished to kill someone, he would take a young man and tell him they could return to Paradise if they entered his service and followed his instructions or died in his service.
And when the Old Man wished to kill someone, he would take him and say: 'Go and do this
thing. I do this because I want to make you return to paradise'. And the assassins go and
perform the deed willingly."
- Marco Polo - on his visit to Alamut in 1273