The Allahdad (Persian: الله داد, transl. 'God's Justice') was an 1839 pogrom perpetrated by Muslims against the Mashhadi Jewish community in the city of Mashhad, Qajar Iran. It was characterized by the mass-killing and forced conversion of the Jews in the area to Islam. Following this event, many of the Mashhadi Jews began to actively practice crypto-Judaism while superficially adhering to Islamic beliefs. The Allahdad incident was a prominent event in the ambivalent history of Jewish–Muslim relations due to the fact that an entire community of Jews were forced to convert, and it was one of the first times European Jewry intervened on behalf of Iranian Jews.