ana
Desert, within the area covered by Indo-Aryan occupation.[277] [See map
page 103.]

[Sidenote: Discontinuous distribution.]

Such broad, intermittent dispersal is the anthropological prototype of
the "discontinuous distribution" of biologists. By this they mean that
certain types of plants and animals occur in widely separated regions,
without the presence of any living representatives in the intermediate
area. But they point to the rock records to show that the type once
occupied the whole territory, till extensive elimination occurred, owing
to changes in climatic or geologic conditions or to sharpened
competition in the struggle for existence, with the result that the type
survived only in detached localities offering a favorable
environment.[278] In animal and plant life, the ice invasion of the
Glacial Age explains most of these islands of survival; in human life,
the invasion of stronger peoples. The Finnish race, which in the ninth
century covered nearly a third of European Russia, has been shattered by
the blows of Slav expansion into numerous fragments which lie scattered
about within the old ethnic boundary from the Arctic Ocean to the
Don-Volga watershed.[279] The encroachments of the whites upon the red
men of America early resulted in their geographical dispersion. The map
showing the distribution of population in 1830 reveals large detached
areas of Indian occupancy embedded in the prevailing white
territory.[280] The rapid compression of the tribal lands and the
introduction of the reservation system resulted in the present
arrangement of yet smaller and more widely scattered groups. Such
islands of survival tend constantly to contract and diminish in number
with the growing progress, density, and land hunger of the surrounding
race. The Kaffir islands and the Hottentot "locations" in South Africa,
large as they now are, will repeat the history of the American Indian
lands, a history of gradual shrinkage and disappearance as territorial
entities.

[Sidenote: Contrasted location.]

Every land contains in close juxtaposition areas of sharply contrasted
cultural, economic and political development, due to the influence of
diverse natural locations emphasizing lines of ethnic cleavage made
perhaps by some great historical struggle. In mountainous countries the
conquered people withdraw to the less accessible heights and leave the
fertile valleys to the victorious intruders. The two races are thus hel