I would be, but YLOD
Anyway, Altair did some stuff that was bad, so Al Mualim killed him, but he lived, but Al Mualim was EVIL so Altair became head of the Hashashin and founded it in its current state.
And Al Mualim had the Apple, and presumably Altair took it.
That's basically all that ACTUALLY happened.
EDIT: Al Mualim was a Templar.