The Bashan site complex comprises over 80 Paleolithic Age sites such as the Yihetou site, Shuimen site and Shuiquanyu site, with the Bashan site in Yishui county, Shandong province at its center. Its discovery and research have established the preliminary cultural sequence of the upper reaches of the Yihe River, spanning from 100,000 to 10,000 years ago.
Over 40,000 relics, comprising 30,000 stone artifacts, over 10,000 animal bones, and a few organic specimens like bamboo or wood, have been unearthed or collected from the site. Notably, a large shovel-shaped straight-tusked elephant (Palaeoloxodon antiquus) ivory artifact discovered at the site appears to be the first of its kind discovered in China.