The date marking the end of prehistory in a particular culture or region, that is, the date when relevant written historical records become a useful academic resource, varies enormously from region to region.
For example, in Egypt it is generally accepted that prehistory ended around 3200 BC, whereas in New Guinea the end of the prehistoric era is set much more recently, at around 1900 AD.
Earlier periods are also called "prehistoric"; there are separate articles for the overall history of the Earth and the history of life before humans.
The period when a culture is written about by others, but has not developed its own writing is often known as the protohistory of the culture.
By definition, This article is concerned with human prehistory, the time since behaviorally and anatomically modern humans first appeared until the beginning of recorded history.
The three-age system is the periodization of human prehistory into three consecutive time periods, named for their respective predominant tool-making technologies: The use of the geologic time scale for pre-human time periods, and of the three-age system for human prehistory, is a system that emerged during the late nineteenth century in the work of British, German and Scandinavian archeologists, antiquarians and anthropologists.
This view has been articulated by advocates of deep history.
The concept of a "Stone Age" is found useful in the archaeology of most of the world, though in the archaeology of the Americas it is called by different names and begins with a Lithic stage, or sometimes Paleo-Indian.
The sub-divisions described below are used for Eurasia, and not consistently across the whole area.
In Europe the relatively well-documented classical cultures of Ancient Greece and Ancient Rome had neighbouring cultures, including the Celts and to a lesser extent the Etruscans, with little or no writing, and historians must decide how much weight to give to the often highly prejudiced accounts of these "prehistoric" cultures in Greek and Roman literature.
In dividing up human prehistory in Eurasia, historians typically use the three-age system, whereas scholars of pre-human time periods typically use the well-defined geologic record and its internationally defined stratum base within the geologic time scale.
They resemble those belonging to “Lucy”, a 3.2 million-year-old skeleton of an extinct primate related to humans and found in Ethiopia.