The two antagonistic geographic forces may be both of the land, one born of a country's topography, the other of its location. Switzerland's history has for centuries shown the conflict of two political policies, one a policy of cantonal and communal independence, which has sprung from the division of that mountainous country into segregated districts, and the other one of political centralization, dictated by the necessity for cooeperation to meet the dangers of Switzerland's central location mid a circle of larger and stronger neighbors. Local geographic conditions within the Swiss territory fixed the national ideal as a league of "sovereign cantons," to use the term of their constitution, enjoying a maximum of individual rights and privileges, and tolerating a minimum of interference from the central authority. Here was physical dismemberment coupled with mutual political repulsion. But a location at the meeting place of French, German, Austrian and Italian frontiers laid upon them the distasteful necessity of union within to withstand aggressions crowding upon them from without. Hence the growth of the Swiss constitution since 1798 has meant a fight of the Confederation against the canton in behalf of general rights, expanding the functions of the central government, contracting those of canton and commune.[16] [Sidenote: Local and remote geographic factors.] Every country forms an independent whole, and as such finds its national history influenced by its local climate, soil, relief, its location whether inland or maritime, its river highways, and its boundaries of mountain, sea, or desert. But it is also a link in a great chain of lands, and therefore may feel a shock or vibration imparted at the remotest end. The gradual desiccation of western Asia which took a fresh start about 2,000 years ago caused that great exodus and displacement of peoples known as the _Voelkerwanderung_, and thus contributed to the downfall of Rome; it was one factor in the Saxon conquest of Britain and the final peopling of central Europe. The impact of the Turkish hordes hurling themselves against the defenses of Constantinople in 1453 was felt only forty years afterward by the far-off shores of savage America. Earlier still it reached England as the revival of learning, and it gave Portugal a shock which started its navigators towards the Cape of Good Hope in their search for a sea route to India. The history of South Africa is intimately connected with the Isthmus of Suez. It owes its Portuguese, Dutch, and English populations to that barrier on the Mediterranean pathway to the Orient; its importance as a way station on the outside route to India fluctuates with every crisis in the history of Suez. [Sidenote: Direct and indirect effects of environment.]