Climatic changes took place in Africa. Gradually the country assumed its present surface of desert and valley. It is supposed that Libyan tribes came from northwestern Africa and settled in Egypt; these were joined later by Asiatic hordes who crossed the Isthmus of Suez in search of better pastures for their flocks, or because of some shifting of the tribes in their rear. This inference, based upon the Semitic elements in the grammar and vocabulary of the language of the earliest Egyptian inscriptions, has been raised almost beyond doubt by the latest researches. From the mingling of these Asiatic tribes with others already established in western Africa, sprang, so it is believed, the early Egyptians. The Egyptians, however, like the ancient Greeks, regarded themselves as autochthonous. Roughly speaking, prehistoric events in Egypt include all those preceding the year 4000 B.C., and our knowledge of them has been gathered from the disclosures of excavated tombs. While a discussion of the Egyptian religion will be taken up later on, some slight knowledge of it is necessary at the start. The Egyptian of both early and later periods believed firmly in a future life, but he believed further that the future welfare of the soul depended wholly upon the preservation of the body. This belief led him to study how best to preserve the dead body, and to bring embalming to such an art that tombs opened today, after the flight of five thousand years, reveal bodies in complete states of preservation. Again, it was believed that the same needs would be felt in the future life as had been experienced during the earthly career. For this reason, foods, vessels of pottery, weapons, and even toilet preparations for personal adornment, were enclosed in the tomb. From a study of the contents of these ancient tombs most that is at present known of the ancient Egyptian has been ascertained. When many implements furnished with ivory handles are found in these tombs, together with occasional pictures of elephants scratched on bone and bits of pottery, even those of us who are neither antiquarians nor historians might infer that the elephant was contemporaneous with the prehistoric Egyptian. Pictures of boats, of animals and men, decorating pieces of pottery, throw light upon this early civilization.