The East Asian seas in the eighteenth century were not, in the slightest, Europe's century. Although the Dutch had seemed, for a time in the seventeenth century, to seize trade hegemony over the East Asian seas, they had never entered the tributary system. When the Dutch tried to purchase sappanwood and tin ore in Siam, or transport goods into Siam, they encountered tremendous difficulties.
First was the increasingly effective royal monopoly. At the time, the Siamese court leaned entirely toward China and granted the Dutch no preferential policies whatsoever.
Second were the Japanese, other European merchants, and Chinese merchants after the lifting of the maritime ban. In the seventeenth century, Toyotomi Hideyoshi began issuing red-seal permits to wealthy merchants in Kyoto, Nagasaki, Osaka, and other places, encouraging them to travel to Annam, Nakhon Si Thammarat, Northern Ayutthaya, and other regions for trade. Before long, Siam became one of the main destinations for Japanese red-seal ships, though they rarely went to southern Siam.
Yet Chinese merchants sometimes faced direct challenges from Japanese and European traders as well. Chinese immigration had existed since the Song dynasty. Because Siamese rice flowed in, aside from tributary envoys, unofficial envoys to Siam were also tacitly approved by the authorities. This forged an unbreakable alliance between the Siamese court and the Qing Dynasty, with Siam serving as something like a transshipment port. Vassal states would hire Chinese as deputy envoys, placing Siam's tributary trade in the hands of a Chaozhou merchant family. Even royal vessels, both within and beyond Siam, were managed by Chinese.
At the same time, the Zheng family of Taiwan used the products of Zhangzhou, Quanzhou, Chaozhou, and Huizhou to trade with Siam. They also bought silver and lead from Japan to pay troops and mint coins, or resold silk to Southeast Asia