In the absence of exact dates, archaeologists have divided the time from the end of the Palaeolithic to the present into the following major periods: Mesolithic period, Neolithic period, Chalcolithic period, Bronze Age, Iron Age, and Modern Age. As has been previously pointed out, this nomenclature has many disadvantages, since the names refer really to cultural stages rather than to periods of time.
The words were first employed in the description of cultures as observed in Europe and the order of succession is not always the same for other continents. Furthermore, it is impossible to assign even estimated dates to these so-called periods, for each one began and ended at a different time in different parts of the world.
On the whole, however, this chronological division does represent the general progress of culture, in the Old World at least, and although it often leads to confusion, unless applied with the greatest care, still it has the advantage of convenience and almost universal usage. The dividing line between prehistory and history comes at no particular place in this series, but varies in different areas.