This defection shows itself most promptly in conquered border tribes of different blood, who lack the bond of ethnic affinity, and whose remoteness emboldens them to throw off the political yoke.  The decay of the Roman Empire, after its last display of energy under Trajan, was registered in the revolt of its peripheral districts beyond the Euphrates, Danube, and Rhine, as also in the rapid Teutonization of eastern Gaul, which here prepared the way for the assertion of independence.  The border satraps of the ancient Persian Empire were constantly revolting, as the history of Asia Minor shows.  Aragon, Old Castile, and Portugal were the first kingdoms in the Iberian Peninsula to throw off Saracen dominion.  Mountain ranges and weary stretches of desert roads enabled the rebellions in Chinese Turkestan and the border districts of Sungaria in 1863 to be maintained for several years.[387]

[Sidenote:  Centrifugal forces on the frontier.]

A feeble grasp upon remote peripheral possessions is often further weakened by the resistance of an immigrant population from beyond the boundary, which brings with it new ideas of government.  This was the geographical history of the Texan revolt.  A location on the far northern outskirts of Mexican territory, some twelve hundred miles from the capital, rendered impossible intelligent government control, the enforcement of the laws, and prompt defence against the Indians.  Remoteness weakened the political cohesion.  More than this, the American ethnic boundary lapped far over eastern Texas, forming that border zone of two-fold race which we have come to know.  This alien stock, antagonistic to the national ideals emanating from the City of Mexico, dominant over the native population by reason of its intelligence, energy, and wealth, ruptured the feeble political bond and asserted the independence of Texas.  Quite similar was the history of the “Independent State of Acre,” which in 1899 grew up just within the Bolivian frontier under the leadership of Brazilian caoutchouc gatherers, resisted the collection of taxes by the Bolivian government, and four years later secured annexation to Brazil.[388]

Even when no alien elements are present to weaken the race bond, if natural barriers intervene to obstruct and retard communications between center and periphery, the frontier community is likely to develop the spirit of defection, especially if its local geographic, and hence social, conditions are markedly different from those of the governing center.  This is the explanation of that demand for independent statehood which was rife in our Trans-Allegheny settlements from 1785 to 1795, and of that separatist movement which advocated political alliance with either the British colonies to the north or the Spanish to the west, because these were nearer and offered easier access to the sea.  A frontier location and an intervening mountain barrier were important factors in the Whisky Rebellion in