ear to year, like that
of the Tunguse Orochon of Siberia who in pursuit of various fish and
game change their residence within their territory from month to month,
or the pastoral nomads who move with the seasons from pasture to
pasture. III. Less systematic outside movements covering the tribal
sphere of influence, such as journeys or voyages to remote hunting or
fishing grounds, forays or piratical descents upon neighboring lands
eventuating usually in conquest, expansion into border regions for
occasional occupation or colonization. IV. Participation in streams of
barter or commerce. V. And at a higher stage in the great currents of
human intercourse, experience, and ideas, which finally compass the
world.[136] In all this series the narrower movement prepares for the
broader, of which it constitutes at once an impulse and a part.

[Sidenote: Importance of such movements in history.]

The real character and importance of these movements have been
appreciated by broad-minded historians. Thucydides elucidates the
conditions leading up to the Peloponnesian War by a description of the
semi-migratory population of Hellas, the exposure of the more fertile
districts to incursions, and the influence of these movements in
differentiating Dorian from Ionian Greece.[137] Johannes von Muller, in
the introduction to his history of Switzerland, assigns to federations
and migrations a conspicuous role in historical development. Edward A.
Ross sees in such movements a thorough-going selective process which
weeds out the unfit, or rather spares only the highly fit. He lays down
the principle that repeated migrations tend to the creation of energetic
races of men. He adds, "This principle may account for the fact that
those branches of a race achieve the most brilliant success which have
wandered the farthest from their ancestral home.... The Arabs and Moors
that skirted Africa and won a home in far-away Spain, developed the most
brilliant of the Saracen civilizations. Hebrews, Dorians, Quirites,
Rajputs, Hovas were far invaders. No communities in classic times
flourished like the cities of Asia created by the overflow from Greece.
Nowhere under the Czar are there such vigorous, progressive communities
as in Siberia."[138] Brinton distinguishes the associative and dispersive
elements in ethnography. The latter is favored by the physical
adaptability of the human race to all climates and external conditions;
it is stimulated by the fo