We as humans are very ignorant of our history, and are only aware of a small percentage. Written records that do exist we ALWAYS doubt, unless we find archaelogical proof, e.g. the Hebrew King David, the existence of Troy, Jerico, etc. Even so, numerous libraries of antiquity have been lost to fire, pilaging and decay. We don't know how they built the pyramids, for there are no records. If it were not for the fact that they still exist, we'd not even be aware that they had been built.