Dindukhi
In India there is caste system even amongst muslims. All the lower caste hindu people who converted to islam in historic time still have the same social class based upon their caste. Mochi, sanke charmers, bear charmers, etc. are the examples. They acquired islam to get higher social status but it was in vain.

Have you heard of Hazra? It is regarded as the lower caste amongst muslims in afghanistan. They are almost treated as untouchables. Do you think a Khan or Sheikh and Qureshi (Butcher caste) have the same social status in islam? Read more!!

And you mentioned muluki ain. Muluki ain enacted by King Mahendra abolished caste based chuwachhut, at least in paper, in Nepal during his reign. So, do not get confused with castist muluki ain of JBR.