Most Isma'ilis outside North Africa, mostly in Iran and the Levant, came to acknowledge Imam Nizar ibn Mustansir Billah's claim to the Imamate as maintained by Hassan-i Sabbah, and this point marks the fundamental split.
Under the leadership of Hassan-i Sabbah and the succeeding lords of Alamut, the strategy of covert capture was successfully replicated at strategic fortresses across Iran, Iraq, and the Fertile Crescent.