The Fatimid Caliphate (909–1171), an Isma'ili Shi'a empire that ruled large parts of North Africa, western Arabia, and the Levant, first from Tunisia (Ifriqiya) and then from Egypt, issued coins after the typical pattern of Islamic coinage. The Fatimids were particularly known for the consistently high quality of their gold dinars, which proved a potent political tool in their conquest of Egypt and led to them being widely imitated by the Crusader states in the 12th century. Fatimid silver coinage (dirhams) on the other hand, although widely issued, declined in quality with the weakening of the Fatimid state, and has been mostly ignored in modern times. The Fatimids minted almost no copper coinage. Starting from designs imitating Abbasid coinage, adapted merely with slogans befitting the new regime and the names of the Fatimid caliphs, from the reign of Caliph al-Mu'izz on, Fatimid coinage included overtly Shi'a formulas and achieved a distinctive look, with concentric inscribed bands, that was maintained until the end of the dynasty.