 Nor was it the lack of warfare, which other historians have suggested to be the case, but does not stand up to scrutiny as walls were a constant factor of war which stood in the way of many Chinese armies since time immemorial into the twentieth century.The answer Andrade provides is simply that Chinese walls were much less vulnerable to bombardment.Andrade argues that traditional Chinese walls were built differently from medieval European walls in ways which made them more resistant to cannon fire.