Shi'ism has been a convenient banner under which the downtrodden could unite in hostility to the ruling Sunni class (whether this was Arab in the person of governors appointed by the caliph, or local rulers in Persia who had retained their Zoroastrian faith and who, when they did not feel strong enough to throw off control, either out of fear of local rivals or of rebellion by their subjects, co-operated with the caliphs). As such, Jaafarism tended to be revolutionary; the first ...