nah, that happened WAY before WWII. i believe those ...

were jewish merchants that went to china during the tang and song dynasties.

as for muslims fighting each other, it's no different from christians fighting each other. european christians fought numerous wars against each other, and similarly, there was the iran-iraq war between two muslim countries in our life time. sometimes, hostility caused by self interest and ethnic tension outweighs having the same religion.