This documentary explains a 2007 discovery of a large mysterious battle that occurred in the Tollense Valley of Germany between 1300 and 1200 BC, a thousand years before writing existed in that area.  So far the remains of more than a thousand people have been uncovered.  Prior to the discovery, evidence of such violence in that part of Bronze Age Europe was almost unheard of, and it appears that one side was using Bronze weapons while the other was using Stone Age weapons, and horses were used in the battle as well.