Prehistory means literally "before history", Human prehistory is the span of time since behaviorally and anatomically modern humans first appear, and until the appearance of recorded history following the invention of writing systems. Since both the time of settlement of modern humans, and the evolution of human civilisations, differ from region to region, prehistory starts and ends at different moments in time, depending on the region concerned. Sumer in Mesopotamia and ancient Egypt were the first civilisations to develop their own scripts, and to keep historical records; this took place already during the early Bronze Age. The neighbouring civilisations of the Ancient Middle East were the first to follow. Most other civilisations reached the end of prehistory during the Iron Age