DOWNFALL AND AFTERMATH

The Assassins were eradicated by the Mongol Empire and the well documented invasion of Khwarizm. They probably dispatched their assassins to kill Mongke Khan. Thus a decree was handed over to the Mongol commander Kitbuqa who began to assault several Hashshashin fortresses in 1253 before Hulagu's advance in 1256. The Mongols besieged Alamut on December 15, 1256. The Assassins recaptured and held Alamut for a few months in 1275, but they were crushed and their political power was lost forever.
The Syrian branch of the Assassins was taken over by the Mamluk Sultan Baibars in 1273. The Mamluks continued to use the services of the remaining Assassins: Ibn Battuta reported in the 14th century their fixed rate of pay per murder. In exchange, they were allowed to exist. Eventually, they resorted to the act of Taqq'iya (dissimulation), hiding their true identities until their Imams would awaken them.
According to the historian Yaqut al-Hamawi, the Böszörmény, (Izmaleita or Ismaili/Nizari) denomination of the Muslims who lived in the Kingdom of Hungary in the 10–13th centuries, were employed as mercenaries by the kings of Hungary. However following the establishment of the Christian Kingdom of Hungary their community was vanquished by the end of the 13th century due to the Inquisitions ordered by the Catholic Church.