Further deterioration in the treatment of Persian Jews occurred during the reign of the Safavids who proclaimed Shi'a Islam the state religion. Shi'ism assigns great importance to the issues of ritual purity ― tahara, and non-Muslims, including Jews, were deemed to be ritually unclean ― najis ― so that physical contact with them would require Shi'as to undertake ritual purification before doing regular prayers. Thus, Persian rulers, and to an even larger extent, the populace, sought to limit physical contact between Muslims and Jews.