While never in a position of power in the central Islamic world, some ‘Alid families succeeded in the ninth and tenth centuries in establishing political rule in parts of North Africa, the Caspian and Yemen. Even though they formed very different kinds of political entities, the basis for the dynasties’ claim to legitimacy was similar: their Prophic lineage. Indeed, all four dynasties – the Fatimids (297/909 - 567/1171), the Idrisids (172/789- 375/985), as well as the Caspian and Yemeni ‘Alids - were Shi‘is of various denominations, to whom religious and political authority was inextricably linked to descent from the Prophet. This paper compares the way in which these dynasties formulated their claims to political and religious authority, and explores some of the similarities and differences between them, examining how far they were in dialogue or competition with each other. In addition to a number of recently available historical and genealogical works, the relatively numerous corpus of coins for all of the dynasties is consulted to draw out some parallels between these very different groupings.