when abundant rainfall and good crops brought on prosperity. In view of all this, Clayton concludes, with justice, I think, that even the small changes of climate incident to the Bruckner cycle have been significant factors in American history. The idea that financial crises and political changes in the United States may be genetically connected with famines and revolts in Asia suggests a hitherto unsuspected unity of history. If the small changes of the Bruckner cycle can produce such important results as those described in the preceding pages, it is clear that the far greater changes of which we have found evidence in Central Asia and elsewhere must have exercised a tremendous influence upon history.
In the dry regions of Chinese Turkestan, we have seen the effect of a change of climate from conditions of comparative aridity to great aridity; in Kashmir, we have seen the opposite effects produced by a change from conditions of extreme coolness and moisture to those of moderate coolness and moisture. The physical change in the two cases was of the same type, from a cooler, moister climate to one that is warmer and drier. The effect on human life, however, was utterly different. In places such as the Chira and Niya regions in Turkestan, the effect of increasing aridity was to drive away the nomads, and to greatly diminish the number of persons supported by agriculture and to reduce them to a somewhat lower stage of civilization. At Endereh, Yartungaz, Lulan, and elsewhere, the result was much more disastrous. Not only did the population decrease enormously, but the few people who remained were compelled to abandon agriculture and to adopt the life of semi-nomadic shepherds or fishermen. All arts decayed, and the people
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