The sixteenth and seventeenth centuries saw the rise of the Safavid dynasty and the establishment of Iran as a stronghold of Shi'a Islam. The body of research on these two centuries of Persian history provides us with a fairly coherent view of the status of religious minorities and their social and economic interactions with Shi'is. The focus of this work will be limited to the concept of najes, or ritual impurity, its application in Shi'a religious law, and its effect on the lives of the ahl al-kitab – People of the Book. I will argue that the application of taboos and restrictive religious laws governing interactions between the ummah and dhimmi populations was unique, or at least original, to the Safavid period, and the relationship between Muslim rulers and dhimmi populations in Iran would never again be the same. The Safavid ulama's focus on this element of Shi'a Sharia had a profound impact on the daily lives of Jews in particular, barring them from particular areas of Islamic society and placing restrictions on their behavior, dress, and economic activity. Manifestations of religious intolerance became more widespread in the advancing years of the Dynasty, which I will argue further weakened Safavid authority and contributed in part to its disintegration. The interpretation and application of religious law in avoidance of najes during the Safavid dynasty was not monolithic, and under each Safavid ruler its emphasis was different. We will explore why this concept came in or out of focus, why the Safavids were unique in their stance on the subject during their time, and how this ideology affected the populations and behavior of religious minorities at different points of Safavid rule.