An answer to /u/shadybunches

The inflow of silver from Spain in the 16th and 17th centuries was useful at a time the Chinese had turned their backs on paper money, which was abused by the Ming government. Another popular form of currency was the copper coin, but this suffered from counterfeiting and production issues, so the government and major traders preferred silver. A major policy in favor of silver was the tax reform called the "single-whip reform", which attempted to consolidate various forms of taxation and thus requiring even more silver as currency.

But it was not all just because of government policy (or government failures). The silk industry was booming, and the arrival of the Europeans further fed this boom. Although Manila was always a small port compared to other ports in the region, it was very important to the Spanish. It comprised a major export from China to Manila. Conversely, silk traders became dependent on Spain's silver. The times that the Manila Galleons failed to make it to Manila from the Americas spelled disaster. The Spanish peso was so well-known in China that there was popular demand for the face of a Spanish king even in coins brought by other European powers!

A short time later, during the so-called mini ice age, silver shipments became unreliable at a time that much rice cultivation was being substituted for silk. This led a double-whammy so to speak, as there was no silver to pay for the silk, at a time that silk and rice production both had declined.

To quote my colleague /u/ParkSunJung , it's as if China had set on a currency for which it has little control over the supply. So it became vulnerable to the supply of silver from Spain, at a time that its alternate supplier Japan was declining in silver production.

Over the longer term, the imbalance between European nations' unwillingness to pay in silver and China's unwillingness to pay for comparable value of European goods led to the Opium war, but that's a century or two away depending on the period of your interest.

Most of the Ming's silver came from Japan instead of the New World.

Cambridge History of China, Vol. 8 Part 2, Chapter 8:

Although reliable figures on overall Japanese bullion production during this period are not available, Testuo Kamiki and Kozo Yamamura have estimated that, between 1560 and about 1600, silver exports from the country averaged between 33,750 and 48,750 kilograms per year. Although this estimate may be high, it is not impossible. Despite interference from the Ming government, which was alarmed by Japanese military power, Japanese and Chinese traders are known to have exported large quantities of silver from Japan to China during this period. They were joined in this activity by the Portuguese, who became important middlemen in Sino-Japanese trade during the mid-sixteenth century. By the 1580s, the Portuguese alone probably were exporting more than 15,000 kilograms of silver from Japan ever year, a total that is thought to have risen substantially by the end of the century.

Exports of Japanese silver continued to expand after the establishment of the Tokugawa Shogunate in 1603.The leading Japanese authority on the subject, Professor Kobata Atsushi, believes that, in some years during the early seventeenth century, combined exports of silver on Japanese, Chinese, Portuguese, and Dutch ships may have reached between 150,000 and 187,500 kilograms. This estimated has been accepted with slight modifications by other experts such as Iwao Seiichi and by Kamiki, and Yamamura. Although Ming government restrictions on direct Sino-Japanese trade meant that much of this silver first had to go to Macao, Taiwan, or Southeast Asia, most of it ended up in China where Chinese merchants early exchanged it for silk, silk and cotton textiles, porcelain, gold, and other goods for the rapidly expanding Japanese domestic market.

This was partly the reason why the Ming collapsed, as after the Tokugawa began limiting trade in the 1630s, the Ming lost a major source of silver and this had a profound impact on the Ming government's fiscal abilities. Loss of Japanese silver meant that silver instead came from Spain and later the British.

Much of this silver went private merchants, but the government also began using silver as currency. The Ming's paper money suffered from inflation so bad that it was almost worthless by the later periods and copper coins were inefficient. In order to restore government finances after decades of fiscal mismanagement, the Grand Secretary Zhang Juzheng instituted the "Single Whip Law" in the 1570s which converted all forms of taxation into silver.

Although there have been some recent arguments to the contrary, there seems little doubt that imports of New World and Japanese silver had a significant impact on the economy of late Ming China. Statistical evidence of that impact can be found in the steep rise in silver receipts recorded by the Ming central government after 1570, in similar rises in silver collections by local governments along the southeastern coast, and in the dramatic changes that occurred in China’s bimetallic rations during the late sixteenth and early seventeenth centuries. For example, although the purchasing power of silver in China for silk, porcelain, and many other products remained very high by world standards, between 1568 and 1644 the gold-silver ration there widened from 1:6 to perhaps 1:10 or even 1:13. Between 1677 and the early 1630s, on the other hand, China’s silver:copper ration narrowed from 1:229 to about 1:112. In both cases, these changes reflect, at least in part, the massive imports of silver discussed above as well as the exports of unminted gold and copper coins that were such important factors in the growth of Ming trade and with Japan and Southeast Asia….

As the pace of that integration increased, Ming China experienced a sharp increase in agricultural specialization and commercialization, rapid growth in the silk, cotton, and porcelain industries, a significant expansion in interregional trade, and the widespread implementation of the so-called “Single-Whip Method” of taxation whereby most land taxes, labor service obligations, and extra levies were commuted to payments in silver.

TL;DR Silver became the de facto official currency of the Ming, it stabilized government finances, promoted interregional and international trade, and integrated China into the world market.