Conversion of China's monetary and fiscal systems to a silver standard led to a doubling in the value of silver in China vis-à-vis the rest of the world by the early sixteenth century. Heightened profit opportunities induced an unprecedented surge in silver production in Spanish America and in Japan. Destined ultimately for China, tens of thousands of tons of silver passed through Europe via long-distance maritime and overland trade routes. Fifty tons of silver annually also reached China via the Pacific Ocean after the founding of the Spanish city of Manila in 1571. Japan exported huge quantities of silver to China until the late seventeenth century. New American crops were also introduced to Chinese agriculture via the Manila galleons, contributing to a doubling or more of Chinese population in the eighteenth century. Silver demand grew along with China's population, which in turn led to a fifty percent silver price premium in China. Largely in response to buoyant demand, more Mexican silver was produced during the eighteenth century than had been produced by all of Spanish America during the sixteenth and seventeenth centuries combined. Subsequently, during the second half of the eighteenth century, a "tea and opium cycle" propelled British fortunes in Asia. Economic, environmental, and demographic histories must not be viewed as independent phenomena. It is a mistake to view societies around the world as independent of or weakly connected to global forces. All heavily populated continents have been deeply connected since the sixteenth century.