The oldest historical site in Austria is at the Gudenus caves in the Kremstal valley, where hunters’ stone implements and bones dating from the Paleolithic Age have been found. The Early Iron Age Hallstatt culture prevailed from around 750–400 BC, covering the area north of the Alps, large parts of Slovakia, the north Balkans and Hungary. This area became renowned for its ceramics, ornamental Hallstatt burial grounds and the development of salt mining.