The birth of Islam over fourteen centuries ago was a monumental event in human history with an everlasting effect on humanity. For centuries, researchers have contemplated on the growth and distribution of Muslims throughout the world. This book presents a reliable estimate of the world Muslim population since the inception of Islam at the start of the seventh century to the end of the twenty-first century. In this book, the world is divided into five continents, each of which is further divided into non-overlapping regions, and these in turn are divided into current countries. A centennial data estimate for each region and current country from 600 AD to 2100 AD (approximately 1 H to 1500 H) of the total population, and the corresponding Muslim population and its percentage are provided. Furthermore, the same data in decennial order from 1790 to 2100 (or 1210 H to 1520 H) is provided for each region and country. These data are summarized to be a reference for other studies and discussions related to the Muslim population.