He claimed to be the first Formosan to visit Europe. For some years he convinced many in Britain, but was later revealed to be an impostor. In 1704 Psalmanazar published a book entitled An Historical and Geographical Description of Formosa, an Island subject to the Emperor of Japan which purported to be a detailed description of Formosan customs, geography and political economy, but which was in fact a complete invention. The "facts" contained in the book were an amalgam of other travel reports, and were especially influenced by accounts of the Aztec and Inca civilization in the New World and by embellished descriptions of Japan. Psalmanazar's book also described the Formosan language and alphabet, which is significant for being an early example of a constructed language. His efforts in this regard were so convincing that German grammarians were including samples of his so-called "Formosan alphabet" in books of languages well into the 18th century, even after his larger imposture had been exposed.

Previously it had been considered a simplified Dutchdialect.