In the old world before 4000 or 5000 B.C., that is to say three or four thousand years earlier, there were primitive civilizations not unlike these American civilizations; civilizations based upon a temple, having a vast quantity of blood sacrifices and with an intensely astronomical priesthood. But in the old world the primitive civilizations reacted upon one another and developed towards the conditions of our own world. In America these primitive civilizations never progressed beyond this primitive stage. Each of them was in a little world of its own. Mexico it seems knew little or nothing of Peru, until the Europeans came to America. The potato, which was the principal food stuff in Peru, was unknown in Mexico. Age by age these peoples lived and marvelled at their gods and made their sacrifices and died. Maya art rose to high levels of decorative beauty. Men made love and tribes made war. Drought and plenty, pestilence and health, followed one another. The priests elaborated their calendar and their sacrificial ritual through long centuries, but made little progress in other directions. XV SUMERIA, EARLY EGYPT AND WRITING The old world is a wider, more varied stage than the new. By 6000 or 7000 B.C. there were already quasi-civilized communities almost at the Peruvian level, appearing in various fertile regions of Asia and in the Nile valley. At that time north Persia and western Turkestan and south Arabia were all more fertile than they are now, and there are traces of very early communities in these regions. It is in lower Mesopotamia however and in Egypt that there first appear cities, temples, systematic irrigation, and evidences of a social organization rising above the level of a mere barbaric village-town. In those days the Euphrates and Tigris flowed by separate mouths into the Persian Gulf, and it was in the country between them that the Sumerians built their first cities. About the same time, for chronology is still vague, the great history of Egypt was beginning. These Sumerians appear to have been a brownish people with prominent noses. They employed a sort of writing that has been deciphered, and their language is now known. They had discovered the use of bronze and they built great tower-like temples of sun-dried brick. The clay of this country is very fine; they used it to write upon, and so it is that their inscriptions have been preserved to us. They had cattle, sheep, goats and asses, but no horses. They fought on foot, in close formation, carrying spears and shields of skin. Their clothing was of wool and they shaved their heads.