Scholars have made contesting claims about the nature and scale of works on religions by Muslim scholars before modern times. The present paper explores various primary and secondary sources, especially the classical bibliographical indexes that the scholarly tradition under scrutiny itself produced, and classifies these works into three types: (a) polemics, (b) works that present authentic knowledge about various faith traditions or introduce methodological novelties but carry some degree of apologetic undertone, and (c) descriptive writings on religions which resemble the modern-day academic study of religion. Based on these distinctions and an assessment of the number of works in each type, the paper maintains that a sprouting tradition of descriptive studies of religions existed in the pre-modern Muslim societies, which introduced certain methodical novelties such as comparative method, historiography, and, last but not least, textual criticism, which seems to have heralded the modern biblical studies in some respects. However, this tradition could not mature into a full-fledged discipline at par with many other branches of knowledge that flourished in the heyday of Muslim civilization. These findings imply that the descriptive study of religions other than one’s own is not necessarily a modern Western phenomenon. It can take root in multiple cultural settings.