Much of the movement of folktales within the area from the Atlantic to the Bay of Bengal has certainly been gradual, extending over centuries of time and thousands of miles. In ordinary times of peace and plenty, the movement was doubtless so slow as sometimes to be almost imperceptible. But when famine or war caused great disturbances of populations, the tales of the people followed them into new areas.

Since the unprecedented shift of peoples beginning in the fifteenth century by the entry of Europeans into Africa and the discovery of America, the folktales of the Old World have made long jumps and find themselves in many alien environments and often in strange enough company. Sometimes these tales have merely remained a part of the tradition of old world descendants in new lands; and sometimes these stories have been so thoroughly taken over by the natives of Africa or the New World that they often seem, on first sight, to be merely a part of the native tradition.