How do we know who's history is right?

History is written by the victor, and it seems that history is also easily maliable. We know that Columbus didn't really find America first, and that the pilgrims probably didn't really have that many peaceful thanksgiving dinners with the Native Americans. Just with the descrepencies of the last 50 years in modern history, how do we honestly know what things in history are factual, which are twists and exaturations, or what are even just flat out lies?