Humans throughout recorded history have used various types of materials as body armor to protect themselves from injury in combat and other dangerous situations. The first protective clothing and shields were made from animal skins. As civilizations became more advanced, wooden shields and then metal shields came into use. Eventually, metal was also used as body armor, what we now refer to as the suit of armor associated with the knights of the Middle Ages. However, with the invention of firearms around 1500, metal body armor became ineffective. Then only real protection available against firearms were stone walls or natural barriers such as rocks, trees, and ditches.