 During the last years of the Wanli era and those of his two successors , an economic crisis developed that was centered on a sudden widespread lack of the empire 's chief medium of exchange : silver . The Portuguese first established trade with China in 1516 , trading Japanese silver for Chinese silk , and after some initial hostilities gained consent from the Ming court in 1557 to settle Macau as their permanent trade base in China . Their role in providing silver was gradually surpassed by the Spanish , while even the Dutch challenged them for control of this trade . Philip IV of Spain ( reigned 1621 – 1665 ) began cracking down on illegal smuggling of silver from New Spain and Peru across the Pacific through the Philippines towards China , in favor of shipping American @-@ mined silver through Spanish ports . In 1639 the new Tokugawa regime of Japan shut down most of its foreign trade with European powers , cutting off another source of silver coming into China . These events occurring at roughly the same time caused a dramatic spike in the value of silver and made paying taxes nearly impossible for most provinces . People began hoarding precious silver as there was progressively less of it , forcing the ratio of the value of copper to silver into a steep decline . In the 1630s a string of one thousand copper coins equaled an ounce of silver ; by 1640 that sum could fetch half an ounce ; and , by 1643 only one @-@ third of an ounce . For peasants this meant economic disaster , since they paid taxes in silver while conducting local trade and crop sales in copper . 
