The days were prehistoric, but of the invasion itself history preserved a tradition. On the walls of the temple of Edfu it is recounted how the followers of Horus, the totem guide and patron deity of the first kings of Upper Egypt, made their way across the eastern desert to the banks of the Nile, and there, with the help of their weapons of metal, subjugated the older inhabitants of the valley. Battle after battle was fought as the invaders slowly pushed their way down the Nile to the Delta, establishing a forge and a sanctuary of Horus on every spot where a victory had been gained.[96] The story has come down to us under a disguise of euhemeristic mythology, but the tradition it embodies has been strikingly confirmed by modern discovery. The “dynastic” Egyptians, the Egyptians, that is to say, who founded the Egyptian monarchy and to whom we owe the great monuments of Egypt, were immigrants from the east. The culture of these “dynastic” Egyptians was built up on two solid foundations, the engineering skill which made Egypt a land of agriculture, and a system of writing which made the organization of the government possible. The culture was at once agricultural and literary, and this alone marked it off from the culture of neolithic (or “prehistoric”) Egypt, which belonged to the desert rather than to the banks and delta of the river, and which knew nothing of writing. Now we have seen that there was one other country in the world in which a similar form of culture had come into existence. In Babylonia too we have a civilization which has as its basis the training of rivers for the purpose of irrigation and the use of a pictorial script. The civilization of Babylonia was, it is true, Sumerian at its outset, but in time it became Semitic, and expressed itself in a Semitic tongue. It is difficult to avoid the conclusion that the Semitic-speaking people who brought the science of irrigation and the art of writing to the banks of the Nile came, like the wheat they cultivated, from the Babylonian plain. There are two archæological facts connected with the early culture of “dynastic” Egypt which seem to me to prove at any rate some kind of intercourse with Babylonia. No building-stone exists in the Babylonian plain; it was therefore the natural home of the art of building in brick, and since every pebble was of value it was also the natural birthplace of the gem-cutter. Nowhere else could the use of clay as a writing material have suggested itself, or that of the inscribed stone cylinder which left its impression behind it when rolled over the clay. Wherever we have the clay tablet and the seal-cylinder we have evidence of Babylonian influence.