Textbooks play a vital role in the Nepali education system since they are one of the main resources for teaching and learning mathematics. Because of poor physical infrastructure and inadequate educational resources, both teachers and students heavily rely on textbooks. In this regard, this study investigated the mathematics textbook authors' experiences and motivation, and what types of didactical knowledge were utilised while writing textbooks. A convenient yet purposeful sampling method was utilised to select four participants. The data analysis unveiled that each textbook author had different types of motivation and experiences, and only one participant was aware of the ideas of didactical knowledge and utilised them to some extent in textbooks. The writing process was more influenced by the examination, mathematical content, and classroom experiences. As a result, textbooks seemed to be content-heavy and examination-oriented. Additional professional development programmes likely would help authors to produce more effective textbooks in Nepal.