the present work deals with circumstances which accompanied the invasion of the Islamic Arab state by Mongols which resulted in the occupation of Baghdad and the downfall of the Abbasid caliphate. The research in an attempt to shed light on the circumstances which prevailed at that time and led to the deterioration of the Abased caliphate The research tries to understand the factors which accumulated and became on the state and to bear further responsibilities which made the measures taken by the caliphuseless finally, the caliphate helplessly surrendered.