sentences:  This differs from old world prehistory where the three-age system, with the Stone Age divided into Paleolithic, Mesolithic, Neolithic, and, Chalcolithic, followed by the Bronze Age and Iron Age, remain in general use.Numerous regional and sub-regional divisions have since been defined to distinguish various cultures through time and space, as later archaeologists recognized that these generalised stages did not adequately correspond to the cultural variation that existed in different locations in the Americas.Today, for Meso- and Andean South America, the later periods are more often classified using the "Horizon" terminology, with "Early Horizon" typically broadly equating to the Late Formative stage.