Since Pingpu indigenous people were the main focus of his missionary work, Maxwell traveled frequently to Aboriginal parishes. There he discovered that contracts for buying and selling of land between Pingpu people and Han Chinese were written using the romanized writing system that was a legacy of the Dutch occupation.
原來，以平埔族為主要對象、經常往來山區教會的馬雅各發現，平埔族和漢人的買賣土地契約書，用的是荷蘭拼音的羅馬字，俗稱為「番仔契」。