It is a commonplace that the great majority of the world's inhabitants are concentrated within a few demographic areas covering only a small portion of the surface of the earth. Of these, perhaps only three are of a first order of magnitude, while easily the greatest of these, the agglomeration in Monsoon Asia, may contain as much as 50 per cent and certainly more than 40 per cent of the world's population. Within this crescent of favored littorals and archipelagoes, certain areas – Japan, China, Java, India, and Tonkin in particular – demonstrate the most delicate and potentially disastrous balance between the physical endowment of an area and the ability of men to win a livelihood and to increase their numbers.