The Monroe Doctrine proved to be the first modern example of what has come to be known as a sphere of influence, or more colloquially, a backyard. The former term was only first used itself in 1867, when Russian diplomat Alexander Gorchakov assured Britain's Lord Clarendon that Afghanistan "lay completely outside the sphere within which Russia might be called to exercise her influence." (At the time, the two countries were caught in midst of the the Great Game, a decades-long struggle between the Russian and British empires for control of Central Asia.) But spheres of influence have a long a storied history that began well before the rise of Europe, from the tributary states of Ming and Qing China to the highly devolved quasi-empire of ancient India's Gupta dynasty....
