In the period that now followed, northern China must have gradually become arid, and the formation of loess seems to have steadily advanced. There is once more a great gap in our knowledge until, about 4000 B.C., we can trace in North China a purely Mongoloid people with a neolithic culture. In place of hunters we find cattle breeders, who are even to some extent agriculturists as well. This may seem an astonishing statement for so early an age. It is a fact, however, that pure pastoral nomadism is exceptional, that normal pastoral nomads have always added a little farming to their cattle-breeding, in order to secure the needed additional food and above all fodder, for the winter. At this time, about 4000 B.C., the other parts of China come into view. The neolithic implements of the various regions of the Far East are far from being uniform; there are various separate cultures. In the north-west of China there is a system of cattle-breeding combined with agriculture, a distinguishing feature being the possession of finely polished axes of rectangular section, with a cutting edge. Farther east, in the north and reaching far to the south, is found a culture with axes of round or oval section. In the south and in the coastal region from Nanking to Tonking, Yünnan to Fukien, and reaching as far as the coasts of Korea and Japan, is a culture with so-called shoulder-axes. Szechwan and Yünnan represented a further independent culture. All these cultures were at first independent. Later the shoulder-axe culture penetrated as far as eastern India. Its people are known to philological research as Austroasiatics, who formed the original stock of the Australian aborigines; they survived in India as the Munda tribes, in Indo-China as the Mon-Khmer, and also remained in pockets on the islands of Indonesia and especially Melanesia. All these peoples had migrated from southern China. The peoples with the oval-axe culture are the so-called Papuan peoples in Melanesia; they, too, migrated from southern China, probably before the others. Both groups influenced the ancient Japanese culture. The rectangular-axe culture of north-west China spread widely, and moved southward, where the Austronesian peoples (from whom the Malays are descended) were its principal constituents, spreading that culture also to Japan. Thus we see here, in this period around 4000 B.C., an extensive mutual penetration of the various cultures all over the Far East, including Japan, which in the palaeolithic age was apparently without or almost without settlers. 5 _The eight principal prehistoric cultures_