[Illustration:  PRIMITIVE INDIAN STOCKS OF SOUTH AMERICA (From Helmolt’s History of the World.  By permission of Dodd, Mead & Co.)]

[Sidenote:  Migrations in relation to zones and heat belts.]

In South America, Caribs and Arawaks showed a strictly tropical distribution from Hayti to the southern watershed of the Amazon.  The Tupis, moving down the Parana-La Plata system, made a short excursion beyond the Tropic of Capricorn, though not beyond the hot belt, then turned equator-ward again along the coast.[195] In North America we find some exceptions to the rule.  For instance, though the main area of the Athapascan stock is found in the frigid belt of Canada and Alaska, north of the annual isotherm of 0 deg.C. (32 deg.F.) small residual fragments of these people are scattered also along the Pacific coast of Oregon and California, marking the old line of march of a large group which drifted southward into Arizona, New Mexico, Texas and the northern part of Mexico.  The Shoshone stock, which originally occupied the Great Basin and western intermontane plateau up to the borders of Canada, sent out offshoots which developed into the ancient civilized tribes of tropical Mexico and Central America.  Both these emigrations to more southern zones were part of the great southward trend characterizing all movements on the Pacific side of the continent, probably from an original ethnic port of entry near Bering Strait; and part also of the general southward drift in search of more genial climate, which landed the van of northern Siouan, Algonquin and Iroquoian stocks in the present area of South Carolina, Georgia, Alabama, Mississippi and Louisiana, while the base of their territory stretched out to its greatest width in southern Canada and contiguous parts of the United States. [See map page 54.][196]

[Illustration:  ETHNOGRAPHICAL MAP OF INDIA FROM THE INDIAN CENSUS OF 1901.]

[Illustration:  ETHNOGRAPHICAL MAP OF ASIA.  Vertical Shading in the North is Slav.]

[Sidenote:  Range of movements in Asia.]

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.