Like most abstract terms, prehistory means different things to different people. For some it means the time before civilization. While I have no quarrel with that definition, it does not get at an essential difference between pre-history and ancient history.
For a civilization to have a history, it must have left written records, at least according to a very literal definition of the word 'history', which comes from the Greek for 'inquiry' and came to mean a written account of events.
Although Herodotus, the Father of History, wrote historically about societies other than his own, in general, a society has a history if it provides its own written record. This requires that the culture has a system of writing and people schooled in the written language. In early ancient cultures, few people had the ability to write. Those who could write were connected with a priestly class. Therefore much ancient writing is connected with that which was religious or holy.
People can devote their entire lives to serving their god(s) or their god(s) in human form. The Egyptian pharaoh was the reincarnation of the god Horus, and the term we use for their picture writing, hieroglyphs, means holy writing (lit. 'carving'). Kings also employed scribes to record their deeds, especially ones that redounded to their glory -- like military conquests. Such writing can be seen on monuments, like stele inscribed with cuneiform.
Those people (and plants and animals) who lived before the invention of writing are, by this definition, prehistoric. Prehistory goes back to the beginning of life or time or the Earth. The area of prehistory is the domain of academic fields with the Greek form arche- 'beginning' or paleo- 'old' attached. Thus, there are fields like archaeology, paleobotany, and paleontology (dealing with the time before people) that look at the world from before the development of writing. As an adjective, prehistoric tends to mean before urban civilization, or simply, uncivilized. Again, prehistoric civilizations tend to be those without written records.
These are working definitions. Classicist Paul MacKendrick published The Mute Stones Speak in 1960. In this and its follow-up two years later, The Greek Stones Speak, he used the non-written findings of archaeologists to help write history. The first was a history of the Italian peninsula, and the second, which used results of the excavations of Troy conducted by Heinrich Schliemann, a history of the Hellenic world.
The dividing line between prehistory and ancient history also varies across the globe. The ancient historic period of Egypt and Sumer started about 3100; perhaps a couple of hundred years later writing began in the Indus Valley. Somewhat later (c. 1650) were the Minoans whose Linear A has not yet been deciphered. Earlier, in 2200, there was a hieroglyphic language in Crete. String writing in Mesoamerica began about 2600 B.C. That we may not be able to translate and make use of the writing is a problem of historians, and would be a worse one if they refused to avail themselves of the non-written evidence. However, by using the pre-literate material, and contributions from other disciplines, especially archaeology, the boundary between prehistory and history is now fluid.
Bronze in the Ancient Aegean
Minoans
Dark Age Time Line
Major Events in Ancient History
Ancient/Classical History Glossary
Introduction to Sumer
Egypt
