Protohistoric may also refer to the transition period between the advent of literacy in a society and the writings of the first historians. The preservation of oral traditions may complicate matters as these can provide a secondary historical source for even earlier events. Colonial sites involving a literate group and a non-literate group, are also studied as protohistoric situations.
In The Oxford Illustrated History of Prehistoric Europe, an article by Timothy Taylor says,
Because of the existence in some but not all societies of historical writing during the first millennium BC, the period has often been termed 'protohistoric' instead of prehistoric. Of course, the understanding of the past gained through archaeology is broadly different in nature to understanding derived from historical texts. Having both sorts of evidence is a boon and a challenge.
In the abstract of a later paper on "slavery in the first millennium Aegean, Carpatho-Balkan and Pontic regions", Taylor, who is primarily an archaeologist, says,
I have taken the rather unusual step of trusting what the classical authors tell us they knew.
For other examples, see also the writings of Brian Fagan on the protohistory of North America and the work of Muhammed Abdul Nayeem on that of the Arabian Peninsula
As with prehistory, determining when a culture may be considered prehistoric or protohistoric is sometimes difficult for the archaeologist. Data vary considerably from culture to culture, region to region, and even from one system of reckoning dates to another.
In its simplest form, protohistory follows the same chronology as prehistory, based on the technological advancement of a particular people with regard to metallurgy:
The best known protohistoric civilizations and ethnic groups are those for whom the term was originally coined: the European barbarian tribes. Many of these peoples of course also experienced periods of prehistory and history.