The Prehistory of West Virginia spans ancient times until the arrival of Europeans in the early 17th century. Hunters ventured into West Virginia's mountain valleys and made temporary camp villages since the Archaic period in the Americas. Many ancient human-made earthen mounds from various mound builder cultures survive, especially in the areas of Moundsville, South Charleston, and Romney. The artifacts uncovered in these areas give evidence of a village society with a tribal trade system culture that included limited cold worked copper. As of 2009, over 12,500 archaeological sites have been documented in West Virginia.