At Nippur they built a great tower of brick to their chief god, El-lil (Enlil), the memory of which is supposed to be preserved in the story of the Tower of Babel. They seem to have been divided up into city states, which warred among themselves and maintained for many centuries their military capacity. Their soldiers carried long spears and shields, and fought in close formation. Sumerians conquered Sumerians. Sumeria remained unconquered by any stranger race for a very long period of time indeed. They developed their civilization, their writing, and their shipping, through a period that may be twice as long as the whole period from the Christian era to the present time. The first of all known empires was that founded by the high priest of the god of the Sumerian city of Erech. It reached, says an inscription at Nippur, from the Lower (Persian Gulf) to the Upper (Mediterranean or Red?) Sea. Among the mud heaps of the Euphrates-Tigris valley the record of that vast period of history, that first half of the Age of Cultivation, is buried. There flourished the first temples and the first priest-rulers that we know of among mankind. § 2B Upon the western edge of this country appeared nomadic tribes of Semitic-speaking peoples who traded, raided, and fought with the Sumerians for many generations. Then arose at last a great leader among these Semites, Sargon (2750 B.C.),[106] who united them, and not only conquered the Sumerians, but extended his rule from beyond the Persian Gulf on the east to the Mediterranean on the west. His own people were called the Akkadians and his empire is called the Sumerian Akkadian Empire. It endured for over two hundred years. But though the Semites conquered and gave a king to the Sumerian cities, it was the Sumerian civilization which prevailed over the simpler Semitic culture. The newcomers learnt the Sumerian writing (the “cuneiform” writing) and the Sumerian language; they set up no Semitic writing of their own. The Sumerian language became for these barbarians the language of knowledge and power, as Latin was the language of knowledge and power among the barbaric peoples of the middle ages in Europe. This Sumerian learning had a very great vitality. It was destined to survive through a long series of conquests and changes that now began in the valley of the two rivers. § 2C As the people of the Sumerian Akkadian Empire lost their political and military vigour, fresh inundations of a warlike people began from the east, the Elamites,[107] while from the west came the Semitic Amorites, pinching the Sumerian Akkadian Empire between them. The Amorites settled in what was at first a small up-river town, named Babylon; and after a hundred years of warfare became masters of all Mesopotamia under a great king, Hammurabi (2100 B.C.), who founded the first Babylonian Empire.