_Abbasids._--In 750 A.D. the Abbasids overthrew the Omayyads, and at first made but superficial alterations in the coinage; the long reverse formula was replaced by the simple profession, "Mohammad is the prophet of God." Plate III. 2, a dinar of the "good" Caliph Harun-al-Rashid (786-809 _A.D._) is typical of the period, except that it bears the name of his ill-fated vizier, Ja'afar, who will be remembered by readers of the _Arabian Nights_ as the companion of the Caliph's nocturnal ramblings, on whom this signal honour was conferred. In the ninth century a second marginal inscription, "To God belongs the order before and after, and in that day the believers shall rejoice in the help of God" (Koran, xxx. 3, 4) was added on the obverse, while the Caliph's name begins to appear regularly on the reverse area. _Contemporaries of the Caliphs._--Coins with similar legends were struck by the various dynasties which arose on the weakening of the authority of the Caliph in the ninth and tenth centuries. In addition to the ruler's name they usually bear the name of the reigning Caliph, whose spiritual authority was still recognised; such are Plate III. 1, a dirhem of the Samanid Nasr b. Ahmad struck in 300 A.H. at Samarkand, which was then one of the great centres of Mohammadan learning and literary activity; Plate III. 4, a Buwayhid dinar of Rukn-al-Daula (932-976 A.D.), struck at Hamadan in 352 A.H., bearing the name of the _fainéant_ Caliph al-Muti; and Plate III. 6, a dinar, struck at Rayy, 447 A.H., of the Great Seljuk Toghrul Beg (1037-1063 A.D.), the Turkish conqueror of Western Asia whose descendants were among the most redoubtable of the "Saracens." Plate III. 3, a dinar of the last Abbasid Caliph--Al-Mustasim (1242-1258 A.D.), illustrates the change in the fabric and calligraphy of the coinage which had taken place in six centuries. Plate III. 5 is a dinar of Mahmud of Ghazni (998-1030 A.D.), with the reverse legend in Sanskrit for the benefit of his Indian subjects.