Hassan-i Sabbah
During the 10th and 11th centuries, Fatimids sent Ismailis Da'i (missioners) to Iran as well as other Muslim lands. When Ismailis divided into two sects, Nizaris established their base in Iran. Hassan-i Sabbah conquered fortresses and captured Alamut in 1090 AD. Nizaris used this fortress until a Mongol raid in 1256.