southern fertile angle of Arabia, known as Yemen. So the Steppes of Arabia, enframing its deserts, serve as a passage-land between the Northern and Southern Heartlands; and there is also the way by the banks of the Nile through Nubia. Thus it will be realised that the Northern Heartland, Arabia, and the Southern Heartland afford a broad, grassy way for horsemen and camel-men from Siberia through Persia, Arabia, and Egypt into the Sudan, and that but for the tsetse-fly and other plagues men would probably have penetrated on horseback and camel-back southward almost to the Cape of Good Hope.
Outside Arabia, the Sahara, and the two Heartlands, there remain in the World-Island only two comparatively small regions, but those two regions are the most important on the Globe. Around the Mediterranean, and in the European peninsulas and islands, there dwell four hundred million people, and in the southern and eastern coastlands of Asia, or, to use the historic expression, in the Indies, there dwell eight hundred million people. In these two regions, therefore, are three-quarters of the people of the world. From our present point of view the most pertinent way of stating this great fact is to say that four-fifths of the population of the Great
