Archaeological research is sometimes categorized according to the time period which it studies. Certain civilizations have attracted so much attention that their study has been specifically named. These subdisciplines include Assyriology (the ancient Near East), Classical archaeology (Greece and Rome), and Egyptology (Egypt). In the United States, all branches concerned with civilizations that left behind written records are called historical archaeology.
Prehistoric archaeology concerns itself with societies that did not have writing systems. The term is generally valid only in Europe and Asia where literate societies emerged without colonial influence. In areas where literacy arrived relatively late, it more convenient to use other terms to divide up the archaeological record. In areas of semi-literacy the term protohistoric archaeology can be adopted to cover the study of societies with very limited written records. One example of a protohistoric site is Fort Ross on the northern California coast, which included settlements of literate Russians and non-literate American Indians and Alaska nativess.
Ethnoarchaeology is the study of modern societies resembling extinct ones of archaeological interest, for archaeological purposes. It is often difficult to infer solid conclusions about the structure and values of ancient societies from their material remains, not only because objects are mute and say little about those who crafted and used them, but also because not all objects survive to be uncovered by scholars of a later age. Ethnoarchaeology seeks to determine, for instance, what kinds of objects used in a living settlement are deposited in middens or other places where they may be preserved, and how likely an object is to be discarded near to the place where it was used.
Taphonomy is the study of how objects decay and degrade over time. This information is critical to interpretation of artifacts and other objects, so that the work of ancient people can be differentiated from the later work of living creatures and elemental forces.
A selective list of subdisciplines distinguished by time period or region of study is given below.
The following is a list of other subdisciplines. Some of these are not areas of study in their own right, and are only methods to be used in larger projects.