This monumental work traces the history of the spread of Islam from its earliest days to the modern era. Thomas W. Arnold, a British orientalist, wrote this book with the aim of explaining how Islam expanded through trade, preaching (da‘wah), education, and social interaction, rather than solely through military conquest. The book discusses the development of Islam in the Middle East, Africa, India, Southeast Asia, and even Europe. With an academic approach, Arnold presents historical evidence showing that many communities embraced Islam due to the exemplary conduct and peaceful interactions of Muslim scholars, merchants, and missionaries. To this day, this work remains an important reference in academic studies on the history of Islamic propagation and its diffusion across various parts of the world.