I have seen many Muslims following caste system. It is Ashraf and Ajlaf. Ashraf consider themselves pure Muslims (like Arabs) and Ajlafs as the converts hence consider them lower.
this is something I am hearing for the first time
I searched for it on net. and this is what I found:
https://en.wikipedia.org/wiki/Caste_system_among_South_Asian_ Muslims
It is ONLY in South Asia........ that too in Places where they have been influenced by the Hindu Caste system. other then that Islam doesn't support this. and it is not also present. there is no caste system in Islam. Knowing Islam, and being a Muslim are two different things. and as a Muslim, I can assure you that there is NO caste system in Islam!! š