E— GEOGRAPHY 119 



prairies which has reached, and perhaps overshot, the cHmatic limits of 

 the region of good cultivable lands. India has made a real expansion 

 on to newly irrigated lands in the Indus Valley. Chinese colonists, to 

 the number of more than thirty millions, have pushed into Manchukwo 

 and Inner Mongolia in the greatest of recent migrations. There has been 

 a similar eastward colonisation from Russia into Western Siberia, in a 

 belt near latitude 55° N. extending almost to Lake Baikal, which may now 

 include twenty million people. But these are only expansions of parts 

 of the populous regions, or in some cases possibly only outward oscilla- 

 tions of their margins ; and they have not seriously altered the relative 

 importance of those major regions with respect either to one another or 

 to the rest of the world. 



Thus the net effect of the great migrations of the nineteenth and 

 twentieth centuries has been to add a fourth to the major populous regions, 

 and then to increase the absolute and relative numbers of the peoples 

 within these four major regions. They have not tended to spread popu- 

 lation more evenly over the lands of the earth or to ' fill up the great open 

 spaces,' but rather to accentuate the crowding of mankind into the already 

 populous lands. ^ 



There has been a very great increase in the numbers of the human race 

 during the last two hundred years. The European peoples have multi- 

 plied at least sixfold since 1700 ; and there is some reason to believe that 

 both Chinese and Indians have at least trebled their numbers in the same 

 period. The world's population is now about two thousand millions ; 

 and it probably did not reach five hundred millions at the beginning of 

 the eighteenth century. But, always with the exception of North America, 

 this increase has been mainly in the already populous Major Human 

 Regions of ' Europe,' India and the Far East, which are the homelands 

 of the three great civilisations ; so that the relative predominance of these 

 regions has rather increased than diminished. So far as the very scanty 

 evidence for Africa goes, it indicates a decrease rather than an increase in 

 the population of that continent, which is only just beginning to recover 

 from the social disasters of the ' Slave Trade.' It is probable that the 

 population of Spanish America declined in the sixteenth and seventeenth 

 centuries. And it is only in the last sixty years that there has been any 

 considerable increase in South America, mainly in the La Plata Region and 

 in southern Brazil. Here the population has more than doubled since 

 1900 ; and the rates of increase in the early decades of this century are 

 quite comparable to those of the United States in the latter half of last 

 century. In the same decades Australia and New Zealand have had similar 

 proportional increases. Nevertheless, the total population of all the lands 

 of the south temperate zone has not yet reached fifty millions ; and the 

 area of good cultivable land in them is so much smaller than that of the 

 great northern regions that they are never likely to be more than minor 

 areas of world population. The figures in the following table (III), 

 p. 120, calculated on the same bases as those in Table II, indicate the 

 comparative importance of these south temperate habitable regions. 



^ These conclusions agree with the views expressed by one of my distinguished 

 predecessors in this chair, Sir Halford Mackinder, at the Centenary Meetingin 1931 . 



