All too often the gallows became the place where the waste and nuisance products of mercantilism—the hungry, poor and far-from-home—were efficiently dispatched
set a beggar on horseback and he'll ride to the Devil
Nobel Prize-winning economist Joseph Stiglitz, dismissing the Federal Reserve’s quantitative easing as a “beggar-thy-neighbor” strategy of currency devaluation, called on America to learn the art of stimulus from China.
Beggar thy neighbour, or beggar-my-neighbour, is an expression in economics describing policy that seeks benefits for one country at the expense of others. Such policies attempt to remedy the economic problems in one country by means which tend to worsen the problems of other countries.
Original applicationThe term was originally devised to characterize policies of trying to cure domestic depression and unemployment by shifting effective demand away from imports onto domestically produced goods, either through tariffs and quotas on imports, or by competitive devaluation. The policy can be associated with mercantilism and the resultant barriers to pan-national single markets.
Extended application"Beggar thy neighbour" strategies of this kind don't apply only to countries: overgrazing provides another example, where the pursuit by individuals or groups of their own interests leads to problems. This dynamic has been called the "tragedy of the commons," though it appears as early as the works of Plato and Aristotle.
According to economist Joan Robinson "beggar they neighbour" policies were widely adopted by major economies during the Great depression of the 1930s. 
The phrase is in widespread use, and is used in such publications as The Economist and BBC News. The term presumably originates from the name of the Beggar-My-Neighbour card game.