The history and culture of a people embody the effects of previous habitats and of their final environment; but this means something more than local geographic conditions.  It involves influences emanating from far beyond the borders.  No country, no continent, no sea, mountain or river is restricted to itself in the influence which it either exercises or receives.  The history of Austria cannot be understood merely from Austrian ground.  Austrian territory is part of the Mediterranean hinterland, and therefore has been linked historically with Rome, Italy, and the Adriatic.  It is a part of the upper Danube Valley and therefore shares much of its history with Bavaria and Germany, while the lower Danube has linked it with the Black Sea, Greece, the Russian steppes, and Asia.  The Asiatic Hungarians have pushed forward their ethnic boundary nearly to Vienna.  The Austrian capital has seen the warring Turks beneath its walls, and shapes its foreign policy with a view to the relative strength of the Sultan and the Czar.

[Sidenote:  Unity of the earth.]

The earth is an inseparable whole.  Each country or sea is physically and historically intelligible only as a portion of that whole.  Currents and wind-systems of the oceans modify the climate of the nearby continents, and direct the first daring navigations of their peoples.  The alternating monsoons of the Indian Ocean guided Arab merchantmen from ancient times back and forth between the Red Sea and the Malabar coast of India.[33] The Equatorial Current and the northeast trade-wind carried the timid ships of Columbus across the Atlantic to America.  The Gulf Stream and the prevailing westerlies later gave English vessels the advantage on the return voyage.  Europe is a part of the Atlantic coast.  This is a fact so significant that the North Atlantic has become a European sea.  The United States also is a part of the Atlantic coast:  this is the dominant fact of American history.  China forms a section of the Pacific rim.  This is the fact back of the geographic distribution of Chinese emigration to Annam, Tonkin, Siam, Malacca, the Philippines, East Indies, Borneo, Australia, Hawaiian Islands, the Pacific Coast States, British Columbia, the Alaskan coast southward from Bristol Bay in Bering Sea, Ecuador and Peru.

As the earth is one, so is humanity.  Its unity of species points to some degree of communication through a long prehistoric past.  Universal history is not entitled to the name unless it embraces all parts of the earth and all peoples, whether savage or civilized.  To fill the gaps in the written record it must turn to ethnology and geography, which by tracing the distribution and movements of primitive peoples can often reconstruct the most important features of their history.

Anthropo-geographic problems are never simple.  They must all be viewed in the long perspective of evolution and the historical past.  They require allowance for the dominance of different geographic factors at different periods, and for a possible range of geographic influences wide as the earth itself.  In the investigator they call for pains-taking analysis and, above all, an open mind.