|Chinese junks 戎克船|
However, it is known that in his youth, Cheng was recruited by the Dutch and worked at Ft Zeelandia as a linguist specializing in Portuguese. During his stay, he apparently learned how the Dutch ruled over the Han and the Aborigines, administered the colony, and how they managed their privateering enterprise, especially in dealing with Min pirates. He then left Taiwan, reportedly without a formal resignation, to take upon the ocean-faring trade, in part imitating the Dutch East India Co ways, soon to command a fleet of 400 junks that sailed up and down the Western Pacific Ocean, from Japan, China, to SE Asia.
Source: Tonio Andrade, "Lost Colony", Princeton Univ Press (2011), pp 26-28