Rituals governing menstruation were an important aspect of Babylonian Jewish life, and they took shape within the context of Sasanian Mesopotamia, where neighboring religious communities were similarly animated by menstruation and its assumed impurity. The Talmud’s Red Fence: Menstruation and Difference in Babylonian Judaism and its Sasanian Context examines how the Talmudic rules of menstruation functioned within the dynamic space of Sasanian Mesopotamia. It argues that difference and differentiation between pure and impure, women and men, gentile and Jew, and the Babylonian and Palestinian Talmuds drove the development and observance of the Talmudic discourse of menstrual impurity, which influences Jewish life to this day. The Talmud’s Red Fence exemplifies Irano-Talmudic research—the effort to understand the Babylonian Talmud within its Sasanian Iranian context. To this end, it reads the Talmud alongside relevant Zoroastrian, Mandaic, and Syriac Christian texts to shed light on this previously overlooked aspect of late antique religious life. The book shows how the Talmudic menstrual rituals developed in conversation with other Sasanian religious communities, especially with Zoroastrians, who had a developed a similarly legalistic discourse of menstrual purity. And it considers the challenges of using an androcentric text to reconstruct a feature of late antique Jewish life that is intimately connected to the female experience.