Anatural border is aborder betweenstates or their subdivisions which is concomitant with natural formations such asrivers ormountain ranges. The "doctrine of natural boundaries" developed in Western culture in the 18th century being based upon the "natural" ideas ofJean-Jacques Rousseau and developing concepts ofnationalism.[1] The similar concept in China developed earlier from natural zones of control.[2]
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Natural borders have historically beenstrategically useful because they are easilydefended. Natural borders remain meaningful in modern warfare even thoughmilitary technology andengineering have somewhat reduced their strategic value.
Expanding until natural borders are reached, and maintaining those borders once conquered, have been a major policy goal for a number of states. For example, theRoman Republic, and later, theRoman Empire expanded continuously until it reached certain natural borders: first theAlps, later theRhine river, theDanube river and theSahara desert. From theMiddle Ages onwards until the 19th century,France sought to expand its borders towards the Alps, thePyrenees, and the Rhine River.[3]
Natural borders can be a source of territorial disputes when they shift. One such example is theRio Grande, which defines part of the border between theUnited States andMexico, whose movement has led tomultiple conflicts.
Natural borders are not to be confused with landscape borders, which are also geographical features that demarcate political boundaries. Although landscape borders, like natural borders, also take forms of forests, water bodies, and mountains, they are manmade instead of natural. Installing a landscape border, usually motivated by demarcatingtreaty-designated political boundaries, goes against nature by modifying the borderland's natural geography. For one, China'sSong Dynasty built an extensive defensive forest in its northern border to thwart the nomadicKhitan people.[4]
In Chapter IV of his 1916bookThe New Europe: Essays in Reconstruction, BritishhistorianArnold J. Toynbee criticized the concept of natural borders.[5] Specifically, Toynbee criticized this concept as providing a justification for launching additional wars so that countries can attain their natural borders.[5] Toynbee also pointed out how once a country attained one set of natural borders, it could subsequently aim to attain another, further set of natural borders; for instance, theGerman Empire set its western natural border at theVosges Mountains in 1871 but duringWorld War I, some Germans began to advocate for even more western natural borders—specifically ones that extend all of the way up toCalais and theEnglish Channel—conveniently justifying the permanent German retention of those Belgian and French territories that Germany had just conquered during World War I.[5] As an alternative to the idea of natural borders, Toynbee proposes making free trade, partnership, and cooperation between various countries with interconnected economies considerably easier so that there would be less need for countries to expand even further—whether to their natural borders or otherwise.[5] In addition, Toynbee advocated making national borders based more on the principle ofnational self-determination—as in, based on which country the people in a particular area or territory actually wanted to live in.[5]