From the inscriptions of Shar-Gâni-sharri and Narâm-Sin that have been brought to light, we gather that the authors of these inscriptions were Semites, in other words we learn that the empire of Agade was a Semitic Empire, and since they extended their empire over all Western Asia, the Sumerian power located more in the south must have proportionately dwindled. But their Sumerian predecessors had established their influence and power in Mesopotamia for a long and indefinite time before this date, for Sumerian inscriptions which are almost certainly to be assigned to the pre-Sargonic period give us the names of a large number of early kings and rulers of Babylonia; their early date is shown by the writing of these inscriptions which bear a more archaic stamp than those of Shar-Gâni-sharri and Narâm-Sin. For just as uninscribed sculptures are relatively dateable by the style of art to which they conform, so that it is possible to provisionally say that this sculpture or cylinder-seal is older than that, because it presents a more archaic and less finished style of art, so is it possible to approximately date un-named and un-dated inscriptions by the style of writing adopted in those inscriptions. We thus have two means at our disposal by which we can assign uninscribed monuments of an early period to their relatively correct places in the evolution of art and culture; on the one hand the stratum of the ruined mound in which the object in question has been found can often itself be relatively dated by actually inscribed monuments found either in the stratum itself, or in the stratum immediately above or below; or failing these, by the depth at which the stratum lies below the top of the mound, though this latter alone is a poor criterion owing to the fact that such accumulation will obviously vary in different places. The value of all such evidence however depends on whether or not the strata have been disturbed, as is often unfortunately the case. The reason why the ruins of Mesopotamian cities have assumed the form of mounds lies in the fact that a conquering chief demolished the clay walls and buildings of his vanquished foe, but instead of clearing the débris away, he built on the top of it; for his new building operations the new-comer often utilized part of the old material, hence the uncertainty of a date assigned to an object, based on the mere assumption that such object belongs to the stratum in which it has ultimately found itself, without other corroborative evidence. On the other hand we are in these days always able to apply the purely archæological test, which depends upon a close examination of the style of art or the mode of writing.