If we turn to the eastern hemisphere, we find the Malays and Malayo-Polynesians, differentiated offshoots of the Mongolian stock, restricted to the Tropics, except where Polynesians have spread to outlying New Zealand. The Chinese draw their political boundary nearly along the Tropic of Cancer, but they have freely lapped over this frontier into Indo-China as far as Singapore.[197] Combined with this expansion was the early infiltration of the Chinese into the Philippines, Borneo, and the western Sunda Isles, all distinctly tropical. The fact that the Chinese show a physical capacity for acclimatization found in no other race explains in part their presence into the Tropics. In contrast, the Aryan folk of India, whether in their pure type as found in the Punjab and Rajputana Desert, or mingled with the earlier Dravidian races belong to the hot belt but scarcely reach the Tropic of Cancer,[198] though their language has far overshot this line both in the Deccan and the Ganges Delta. One spore of Aryan stock, in about 450 B.C., moved by sea from the Bay of Cambay to Ceylon; mingling there with the Tamil natives, they became the progenitors of the Singhalese, forming a hybrid tropical offshoot. Europe, except for its small sub-arctic area, has received immigrants, according to the testimony of history and ethnology, only from the temperate parts of Asia and Africa, with the one exception of the Saracens of Arabia, whose original home lay wholly within the hot climate belt of 20 deg.C. (68 deg.F.). Saracen expansion, in covering Persia, Syria, and Egypt, still kept to this hot belt; only in the Barbary Coast of Africa and in Spain did it protrude into the temperate belt. Though this last territory was extra-tropical, it was essentially semi-arid and sub-tropical in temperature, like the dry trade-wind belt whence the Saracens had sprung. [Illustration: ETHNOGRAPHICAL MAP OF AFRICA AND ARABIA.] [Sidenote: Range of movements in Africa.]