Usually, the diagnostic set of artifacts consists primarily of pottery. Pottery sherds are the most abundant artifacts found at sites in Mesopotamia and Egypt during the periods we are studying in this class. The type of clay used in pottery production, the method of production, and the designs on pottery change over time and across regions. Changes in the type and distribution of pottery across a region are often used by archaeologists to distinguish between different periods. The number and form of pottery vessels evolves.
Some periods have larger numbers of bowls than jars.
Changes in architecture can also be characteristic of certain periods. For instance, some periods in Mesopotamia are marked by changes in the shape of mudbricks and in Egypt the elaboration of tombs culminating in the Giza pyramids distinguish architecture from different periods. Many objects, then, can make up a characteristic set of objects for a period, however many of the ways of describing these artifacts are qualitative and therefore open to debate. The style of a particular piece of art cannot be entirely quantitatively determined. Also, ratios of different types of artifacts, like pottery forms, can indicate functional as well as chronological differences.