Today in excavating one of these mounds where once an ancient city lay, great care must be taken as one digs by hand to take each load of dirt and sift it through a screen to one side from the mound to be sure nothing is missed. Thus layer by layer it is lowered to its original virgin soil. Obviously, the farther down one digs the older the civilization would be which occupied the site. Different nationalities at different ages had their own distinctive designs for pottery or methods of making tools. Once the archaeologist learns the types of pottery for the different ages he can find a small piece of clay pot and tell something about the people who made it.
Bones are an excellent means of telling the kind of people who lived at the site at a given time.
Animal bones indicate what they ate and what domestic animals they had. The time of the arrival of the camel or horse has played a major role in chronology. The presence of diseases such as arthritis and abscesses in the teeth further reveals life on the passing scene. Methods of burial reveal something about their religious beliefs. Thus, even in pre-historic times before men wrote, they left their records for the modern student of history.