There have been repeated efforts to discover, by measurements of various kinds, further and more decisive differences which would serve as really scientific determinants of race. Gradually these efforts have been given up. To-day we realize that there are no hard and fast racial types among men. Race is a dynamic and not a static conception, and the typical races are continually changing and developing, amalgamating and differentiating. In this little book, then, we are studying the history of the darker part of the human family, which is separated from the rest of mankind by no absolute physical line, but which nevertheless forms, as a mass, a social group distinct in history, appearance, and to some extent in spiritual gift. We cannot study Africa without, however, noting some of the other races concerned in its history, particularly the Asiatic Semites. The intercourse of Africa with Arabia and other parts of Asia has been so close and long-continued that it is impossible to-day to disentangle the blood relationships. Negro blood certainly appears in strong strain among the Semites, and the obvious mulatto groups in Africa, arising from ancient and modern mingling of Semite and Negro, has given rise to the term "Hamite," under cover of which millions of Negroids have been characteristically transferred to the "white" race by some eager scientists. The earliest Semites came to Africa across the Red Sea. The Phoenicians came along the northern coasts a thousand years before Christ and began settlements which culminated in Carthage and extended down the Atlantic shores of North Africa nearly to the Gulf of Guinea. From the earliest times the Greeks have been in contact with Africa as visitors, traders, and colonists, and the Persian influence came with Cambyses and others. Roman Africa was bounded by the desert, but at times came into contact with the blacks across the Sahara and in the valley of the Nile. After the breaking up of the Roman Empire the Greek and Latin Christians filtered through Africa, followed finally by a Germanic invasion in 429 A.D. In the seventh century the All-Mother, Asia, claimed Africa again for her own and blew a cloud of Semitic Mohammedanism all across North Africa, veiling the dark continent from Europe for a thousand years and converting vast masses of the blacks to Islam. The Portuguese began to raise the veil in the fifteenth century, sailing down the Atlantic coast and initiating the modern slave trade. The Spanish, French, Dutch, and English followed them, but as traders in men rather than explorers.