The oldest and longest division of the Three-Age System, preceding the Bronze Age and Iron Age, the oldest known period of human culture - characterized by the use of stone tools. This prehistoric age embraces the Paleolithic (Old), Mesolithic (Middle), and Neolithic (New). These three separate periods are based on the degree of sophistication in the fashioning and use of tools. Metals were unknown, but tools and weapons were also made of wood, bone, and antler. The dates for the Stone Age vary considerably from one region to another, and some communities were still living a Stone Age life until very recent time. In sub-Saharan Africa, the Stone Age is equivalent to the term Palaeolithic, and spans c 2.5 mya until the 19th century AD.