I expected to see some mention of the Opium Wars.
I once had an American “trade dollar” that was meant for the China trade. It had a bIt more silver than a regular dollar and had “chop” marks on it. We tend to forget that New Spain/Mexico was far richer than the U.S. for a long time.
The book “1493” has chapters on this. The Spanish sent annual Manila Galleon(s) from Acapulco loaded with silver across the Pacific to trade with Chinese merchants in Manila. The ships came back to Acapulco loaded with porcelains, silks and whatever other Chinese goods Europeans were crazy for. These goods would travel overland through Mexico City to Veracruz to be shipped back to Europe. The Spanish sent around a quarter of their silver from the Americas to China. In an attempt to stop this leakage Madrid placed limits on how many ships could participate in the Manila trade. In response, some of largest ships of the era were built to handle this trade. The Spanish knew there was a trading bay in the Phillipines were Chinese merchants gathered to trade with merchants. They discovered this bay and conquered to monopolize this trade. As with most of history the Chinese were not interested in overseas products so silver kept flowing into China having massive effects on the economy. The British eventually solved this problem by getting the Chinese hooked on opium. One can find American and British silver trade dollars on e-bay. Their relative unpopularity explains why these silver coins are in good shape. The British silver dollar weighed around .9 oz.