797-798 Continued victories over the Byzantines cause the empress Irene to sue for peace. The Khazars driven out of Armenia. 800 The Aglabite dynasty founded at Kairwan. 801 Harun sends an embassy to Charlemagne. 802 The emperor Nicephorus refuses to continue payment of tribute. Harun makes such a devastating invasion of Asia Minor that Nicephorus sues for peace. He breaks it the next year, and the same process is repeated. 804-805 Rebellion in Khorasan. 806 Peace renewed with Nicephorus after hostilities have once more been begun. 808 Edrisite dynasty founded at Fez. 809 Death of Harun on the way to quell disturbances in Khorasan. His reign is a flourishing period of art and science. His son, =Emin=, succeeds. His reign is mostly taken up with the rebellion of his brother, Mamun, who gradually wins all the provinces, except Baghdad, to his side. 813 Capture and assassination of Emin. =Mamun= proclaimed at Baghdad. The civil war continues. 817 Mamun appoints Musa b. Ali heir to the throne, whereupon the people of Baghdad declare Mamun deposed and elect his uncle, Ibrahim, caliph. Sudden death of Musa. 820 Appointment of Tahir as governor of Khorasan, where his descendants rule until 872--sometimes called Tahirite dynasty. 829 Euphemius invites the Mohammedans from Africa into Sicily. They take Palermo. 831 The Mohammedans begin a long invasion of Asia Minor. 832 Capture of Heraclea. 833 Death of Mamun. His reign is the Augustan age of Arabian literature. Works on science and philosophy translated from the Greek. Mamun orders the measurement of a degree of the earth’s circumference. The designated heir, his brother =Mutasim=, succeeds. A party in favour of Mamun’s son, Abbas, is put down. Mutasim employs Turks in his body-guard, and their excesses cause Baghdad to revolt. The caliph removes the capital to Samarra. 836 The emperor Theophilus destroys Zapetra in his savage war on the Moslems. 838 Moslem victory at Dasymon. Amorium captured. Second revolt of Abbas, who dies in prison. 841 Death of Mutasim. His son, =Wathik=, succeeds. The caliphate begins to decline. 845 Truce with the empress Theodora. 847 Death of Wathik. The state officials elect his son, Muhammed, to succeed, but immediately recall their choice and substitute Wathik’s brother, =Mutawakkil=. He is noteworthy for his atrocious cruelty, and persecutes the Jews and Christians. 852 Serious revolt in Armenia suppressed in four years. 858 A great war with the Byzantines begins in Asia Minor. The Mohammedans capture the Byzantine commander. 860 Byzantine defeat near Melitene. 861 Murder of Mutawakkil by his Turkish guard, bribed by his son, =Muntasir=, who takes the caliphate.