(12) Nabuna’id, King of Babylon, 555-538 B. C., states that he found, in repairing the temple at Sippar (Agade), the temple-platform of Naram-Sin, son of Sargon, which no one had seen for 3,200 years. As he made this statement about 550 B. C., it was long supposed that this fixed the date of Naram-Sin as 3750 B. C., and that of his father, Sargon, at about 3800 B. C. These dates will be found in many of the older books, but they are incredible. They would, if true, leave long gaps in the history that we have no information to fill. Since it has been clearly proved that the dynasties overlapped, it seems that Nabuna’id reached his date by adding together the totals of dynasties, some of which were contemporary. It now seems probable that he placed Naram-Sin about 1,100 years too early. The sources here enumerated afford us a tolerably accurate chronology back to about 2450 B. C. All dates earlier than this have to be estimated by combining statements of early dynastic tablets with archæological and palæographic considerations. =6. Outline of the History.=--The history of Babylonia and Assyria falls into eight different periods. Our information is not yet sufficiently complete to enable us to write the history of any one of them, but we can discern in outline a most fascinating course of events. (1) _The Prehistoric Period_, or the period before the rise of written history, during which we can ascertain from various inferences the general course of events. This period must have begun about 4500 or 5000 B. C. and lasted down to about 3200 B. C. The Semites from Arabia[13] were the first to pour into the fertile valley of Mesopotamia. They came up from the south, establishing the city of Eridu on the shore of the Persian Gulf, then the cities of Ur, Erech, Lagash, Nippur, etc. They carried with them the culture of the palm-tree, and learned to raise grain in the alluvial soil of the rivers, but they had no system of writing. The early cities of Babylonia were the fortified residences of different tribes, which were frequently at war with one another. One city would subjugate its neighbors for a time and establish a small empire. As long as it continued to rule, a certain degree of homage was paid to its god by all the cities over which it ruled. In prehistoric times there were kingdoms of this sort ruled at one time by Eridu, at another by Erech, and at another by Nippur, for Ea, the god of Eridu, Anu, the god of Erech, and Enlil or Bel, god of Nippur, were ever after worshiped as the supreme gods of Babylonia.