Although the earliest Sumerian settlements in Southern Babylonia are to be set back in a comparatively remote period, the race by which they were founded appears at that time to have already attained to a high level of culture. We find them building houses for themselves and temples for their gods of burnt and unburnt brick. They are rich in sheep and cattle, and they have increased the natural fertility of their country by means of a regular system of canals and irrigation-channels. It is true that at this time their sculpture shared the rude character of their pottery, but their main achievement, the invention of a system of writing by means of lines and wedges, is in itself sufficient indication of their comparatively advanced state of civilization. Derived originally from picture-characters, the signs themselves, even in the earliest and most primitive inscriptions as yet recovered, have already lost to a great extent their pictorial character, while we find them employed not only as ideograms to express ideas, but also phonetically for syllables. The use of this complicated system of writing by the early Sumerians presupposes an extremely long period of previous development. This may well have taken place in their original home, before they entered the Babylonian plain. In any case, we must set back in the remote past the beginnings of this ancient people, and we may probably picture their first settlement in the neighbourhood of the Persian Gulf some centuries before the period to which we may assign the earliest of their remains that have actually come down to us.