Amoy, present-day Xiamen, was a port city on the eponymous island at China's southeast coast. After the VOC had settled on Taiwan in 1624, hoping to be able to set up regular trade with China from there, they were regularly active in the area around Xiamen. This area was the power base of the Zheng clan, a mighty maritime faction with much influence on the China Sea and along the coast, with which the VOC had a rather tenuous relationship. In the 1630s, the VOC fought several battles near the islands, sometimes as an ally of clan leader Zheng Zhilong, sometimes as his enemy.
After the fall of the Ming Dynasty (1644) Zhilong's son, Zheng Chenggong (known in the Dutch sources as Koxinga) became the dominant power in the region. From the nearby island of Jinmen (known in Dutch sources as Quemoy), he launched an invasion of Taiwan in 1661, which would drive the Dutch from the region.
The river which floats out onto the ocean just west of Xiamen, the Jiulong, was known to the Dutch as the Chincheo.
Nowadays, Xiamen is Chinese territory, whereas Jinmen is Taiwanese.