family and relatives in 1371; the foreign ports of Guangzhou, Quanzhou, and Ningbo were closed in 1384. After the ´voyages to the western oceans´ between 1405 and 1433, which had shown China to be technically ahead shipbuilding, a restrictive closed-door policy towards long-distance trade was adopted. Legal trade was restricted to tribute delegations sent to or by official representatives of foreign governments, although this took on an epic scale under the Yongle Emperor with Zheng He's treasure voyages to Southeast Asia, India, and eastern Africa. The policies exacerbated "Japanese" piracy along the coasts, with many Chinese merchants joining their ranks in an illegal trade network the Ming were unable to curtail. The sea bans were finally ended in 1567, with trade only prohibited to states at war with the throne. Needham estimated the trade between the end of the ban and the end of the dynasty (1567–1644) at about 300 million taels. In addition to small base-metal coins, the Ming issued fiat paper currency as the standard currency from the beginning of the reign until 1450, by which point – like its predecessors – it was suffering from hyperinflation and rampant counterfeiting. (In 1425, Ming notes were trading at about 0.014% of its original value under the Hongwu Emperor.) Monetary needs were initially met by bullion trading in silver sycee, but a shortage of silver in the mid-15th century caused a severe monetary contraction and forced a great deal of trade to be conducted by barter. After the single whip law substituted silver instead of rice as the means of paying taxes, China, which had not been much interested in European or Japanese goods, found that the silver of Iwami Ginzan and Potosí was too profitable and important to restrict. Inflows of Japanese (imported via Macau by the Portuguese) and Spanish silver (brought by the Manila galleons) monetized China's economy, and Spanish dollars became a common medium of exchange. China was part of the global silver trade. The size of the late Ming economy is a matter of conjecture, with Twitchett claiming it to be the largest and wealthiest nation on earth and Maddison estimating its per capita GDP as average within Asia and lower than Europe's. Ming industry After 1400, Ming China's economic recovery led to high economic growth and the revival of heavy industries such as coal and iron. Industrial output reached new heights surpassing that of the