User blog comment:JorgeGG/Dar al-Islam (or Al-Umam Al-Muttahida)/@comment-1630894-20111007021534/@comment-1310192-20111013194403

After some research, yes, you're right, I was completely wrong about the Zheng He thing. Scrap that.

However, the Muslims did have some advantages over the Natives even without gunpowder; they still had better armour, steel (AFAIK far more resistant than obsidian when it comes to war), horses and smallpox and their slight defenses against it, which were the cause for the death of much of the Indians after conquest. Besides, most native tribes (the great civilizations are not, but I mean the Powhatan, Quimbaya, Taínos et al) were friendly towards the new Europeans; that might also give some of an advantage to Muslim conquest. The possibilities are far lower than they were OTL, but it still could happen.