During the 17th century, the European have been sailed to Asia to develop their trade. Formosa then has become one of the most important transit ports in the East Asian, and Fort Zeelandia has been an international business center. On behalf of the Dutch East India Company, the ships departed from Formosa, north forward to Japan, west to Fujian, south to Vietnam, Thailand, and Indonesia, India, Iran or Europe.
The Dutch chose a sandy peninsula off the coast of Tainan as the site of the fortress since this would allow the fortress direct access to the sea and with it, supplies and reinforcements from Batavia in event of a siege. Unfortunately, the site chosen lacked adequate supplies of fresh water, which had to be shipped in from the mainland.
The importance of Anpings geographical position is obvious, and can be seen from its depiction on an ancient map. According to the topography, there were a series of sandbars that extended from south to north; the east side of such sandbars was the Taijian Inner Sea. Fort Zeelandia was established on the largest sandbar to control the channel for entering the inner sea. The Taijian Inner Sea was also a good harbor for docking vessels.