Infighting among the sees, and particularly the rivalry between Rome (which considered itself preeminent over all the church) and Constantinople (which came to hold sway over the other Eastern sees and which saw itself as equal to Rome, with Rome "first among equals"), prevented the pentarchy from ever becoming a functioning administrative reality. The Islamic conquests of Alexandria, Jerusalem, and Antioch in the 7th century left Constantinople the only practical authority in the East, and afterward the concept of a "pentarchy" retained little more than symbolic significance.