The Abbasid caliph al-Mutawakkil was assassinated by his guards, beginning the Anarchy at Samarra. Abbasid Caliphate: The Abbasid Caliphate or Abbasid Empire was the third Islamic caliphate, ruled by the Abbasid dynasty. The dynasty was descended from Muhammad's uncle, Abbas ibn Abd al-Muttalib, after whom it is named. The Abbasids rose to power in 750, when the Abbasid Revolution overthrew the preceding Umayyad Caliphate. They ruled as caliphs from their base in Iraq until 1258, with Baghdad as their capital for most of their history. December 11, 861. Wiki link