ABBASIDS, the name generally given to the second of the two great dynasties of the Mohammedan empire. The Abbasid caliphs based their claim on their descent from Abbas (A.D. 566— 652), the eldest uncle of Mohammed, and regarded themselves as the true heirs of the Prophet as opposed to the descendants of Omayya. Throughout the second period of the Omayyads, repre sentatives of this family were among their most dangerous oppon ents. In the reign of Merwan II. this opposition culminated in the rebellion of Ibrahim the Imam who achieved considerable suc cess, but was captured (A.D. 747) and died in prison. The quarrel was taken up by his brother Abdallah, who after a decisive vic tory on the Greater Zab (75o) finally crushed the Omayyads and was proclaimed caliph.
The new dynasty encouraged the development of luxury and the liberal arts. The reigns of Harun al-Rashid (786-809) and Mamun (813-833) at Baghdad were periods of extraordinary splendour. But the empire as a whole stagnated and then decayed. Independent monarchs established themselves in Africa and Khfi rasan. The ruin of the dynasty came, however, from those Turkish slaves who were constituted as a royal bodyguard by Moqtasim (833-842). Their power grew until Radi (934-941) was con strained to hand over most of the royal functions to Mohammed b. Raik. Province after province renounced the authority of the caliphs, who were merely lay figures, and finally Khulagu, the Tatar chief, burned Baghdad (Feb. 28, 1258). The Abbasids still maintained a feeble show of authority, confined to religious mat ters, in Egypt under the Mamelukes, but the dynasty finally dis appeared when Motawakkil III. was carried as a prisoner to Con stantinople by Selim I. (See CALIPHATE.) `ABBAS MIRZA ( 783-1833) , Persian prince, was a younger son of Feth Ali, shah of Persia, and was nominated to succeed him. But he predeceased his father and the succession fell to his son, Mohammed Mirza. 'Abbas Mirza conducted many campaigns against Russia between 1800 and 1813 when, by the Treaty of Gulistan, Georgia and other provinces were ceded to Russia. In 1826-28 he and his son were again campaigning against Russia, again with no final success, for the khanates of Erivan and Nakhichevan were ceded to Russia. In the interval of the Russian wars he fought against the Turks, winning a complete victory near Erzerum in 1821. After the final peace with Russia 'Abbas Mirza set about the reorganization of the province of Khurasan and died at Meshed in Dec. 1833. Although 'Abbas was unsuccess ful in the wars against Russia, he displayed great skill as a general, and learned something from the European soldiers who helped him to reorganize his army. He was cultivated and intelli gent, and lived more simply than was the custom with the Persian royal house.