Portugal commenced after the Portuguese occupation of Macau in 1557 and two decades later trade with Castile was established, trade with the Dutch Republic started in 1604 with their occupation of the Penghu islands, and with the Kingdom of Great Britain in 1729. By the end of the eighteenth century China was also trading with the newly established United States of America. Despite Chinese merchants valuing both foreign silver coins (銀元) and Chinese silver ingots (銀兩) based on their silver content, the government of the Qing dynasty still enforced the opinion that the silver coins that originated in foreign countries was somehow of inferior value than the Chinese sycees. Yet the private Chinese markets didn't share this opinion with the imperial Qing government as the populations of the coastal provinces (and Guangdong most in particular) held the foreign silver coins in high esteem due to various advantages such as their fixed nominal values and their consistently reliable fineness of their silver content which all made them be used for transactions without having to undergo a process of assaying or weighing as is expected of sycees. The year 1814 the market value of 1 silver foreign coin in Guangzhou was never less than 723 Chinese cash coins, while in other provinces like Jiangsu and Zhejiang they were even worth more eight hundred cash coins, or foreign silver coins could be traded for 0.73 tael of silver each. The following decades the exchange ratee would only rise and a single foreign silver coin would be worth between 1,500 and 1,900 Chinese cash coins. The Chinese authorities during this period for this reason often raised the proposition to ban the circulation of foreign silver coins within Chinese territory, on the suspicion that "good" Chinese silver went to foreign markets, while the "inferior" foreign silver coins caused the markets of southern China to inundate. There was evidence that the Qing dynasty indeed suffered a net loss of 11% when changing Chinese into foreign silver. During the initial period of the 19th century the imperial Chinese administration suspected that more silver was being exported than imported causing the Chinese to slowly develop a silver deficit as the trade balance fell on the negative side of the spectrum for the Qing. However, as the government of the Qing dynasty never collected and compiled any statistics on the private trade of silver it is very difficult to