In a blog post by Raymond Ibrahim he states the following about Muhammad and the early years of islam:
After more than a decade of peaceful preaching in Mecca, he had won over only some 100 followers, mostly relatives. Once, however, he took to raiding and plundering all who rejected his Islam — and became immensely successful at it — his followers grew exponentially.
While it is evident from history that islam has mostly gained followers by way of war (jihad), conquest and politics over the course of centuries, is Raymond Ibrahim correct to claim that in its early years (before armed conflict), the spread of islam was rather diminutive? Was it limited to Muhammad's own tribe? How did Muhammad preach and why was his preaching not effective?