of America, prior to 1763, held a long cordon of coast, hemmed in
between the Appalachian Mountains and the sea. Despite threats of French
encroachments from the interior, they expanded from this narrow
peripheral base into the heart of the continent, and after the
Revolution reached the Mississippi River and the northern boundary of
the Spanish Floridas. They now held a central location in relation to
the long Spanish periphery of the Gulf of Mexico. True to the instincts
of that location, they began to throw the weight of their vast
hinterland against the weak coastal barrier. This gave way, either to
forcible appropriation of territory or diplomacy or war, till the United
States had incorporated in her own territory the peripheral lands of the
Gulf from Florida Strait to the Rio Grande. [See map page 156.]

[Sidenote: Russian expansion in Asia.]

In Asia this same process has been perennial and on a far greater scale.
The big arid core of that continent, containing many million square
miles, has been charged with an expansive force. From the appearance of
the Aryans in the Indus Valley and the Scythians on the borders of
Macedonia, it has sent out hordes to overwhelm the peripheral lands from
the Yellow Sea to the Black, and from the Indian Ocean to the White
Sea.[251] To-day Russia is making history there on the pattern set by
geographic conditions. From her most southerly province in Trans-Caspia,
conquered a short twenty-five years ago, she is heading towards the
Indian Ocean. The Anglo-Russian convention of August 31st, 1907,
yielding to Russia all northern Persia as her sphere of influence,
enables her to advance half way to the Persian Gulf, though British
statesmen regard it as a check upon her ambition, because England has
secured right to the littoral. But Russia by this great stride toward
her goal is working with causes, satisfied to let the effects follow at