Nadir Shah took the throne of Iran after two centuries of Safavid control; but without political legitimacy. Ascending from obscurity and without dynastic credentials, Nadir tried and failed to establish his right to rule the people of Iran from the 1720s until 1747. This biography of Nadir - the first scholarly study of its subject since 1938 - tells how Nadir Shah's novel strategies influenced successive rulers of Iran in their own defense of power. The Safavids had based their legitimacy on claims of descent from the seventh Imam and their role as defenders of Twelver Shi'ism. Nadir Shah sought to legitimize himself by recasting religious and ethnic differences in ideological terms. This new study relies on documents in the Ottoman archives to assess Nadir's reign in a new light. Though Nadir's schemes did not find acceptance, they were among the first attempts to define political legitimacy in Iran in a modern context, and they would influence the country's politics centuries later. Scholars will find this book fills an enormous gap in understanding Iranian history.