There’s a wonderful book by S. Frederick Starr, “Lost Enlightenment,” that includes Avicenna as part of a larger history of Central Asia’s part in helping to shape a form of Islam very different from the type of doctrinaire fundamentalism Westerners think of today: liberal, open to questioning and varied interpretations, science-friendly and more. Also the story of the pushback of more conservative schools of thought, often based in older parts of the Muslim world which sought to maintain religious and political control of the growing faith, which eventually prevailed.