836 – Samarra established and the Abbasid caliph Al-Mu'tasim relocated capital from Baghdad to Samarra.[1][2] 848 – Great Mosque of Samarra built [3] 859 – Abu Dulaf Mosque built [4] 861 – 11 December: Caliph Al-Mutawakkil assassinated.[5][6] 868 – The Islamic scholar and the 10th imam from the Twelve Imams Ali al-Hadi died in Samarra on 21 June.[7][8][9][10][11][12] 861 – 870 Caliphal Civil War, was an armed conflict during the "Anarchy at Samarra" [13][14] 874 – The Islamic scholar and the 11th imam from the Twelve Imams Hasan al-Askari died in Samarra on 4 January[15] 892 – Abbasid caliph Al-Mu'tamid relocated capital to Baghdad from Samarra.[1] 1258 – Samarra occupied by Mongol Empire forces[16]