major problems faced by enemies of mongols were their arrows could not bring them down. mongol cavalry were reported to fight normally while being covered in 50+ arrows. the same problem was problem was faced by jin archer conscripts who could not penetrate the 4 inch thick tower shields of general yue feis army, and likewise chinese archers who could not penetrate double lamenar armor of jin iron tower cataphract and hammer cavalry. this was what pushed for the development of firearms