While you wait for fresh answers from qualified experts, you may be interested in some past threads concerning this topic

Pre-Civil rights movement in the states, how were other races segregated? ( i.e hispanic, asian) Did all POC Go to "black" Schools? with a response by /u/UrAccountabilibuddy

How were non-black minorities treated in the Jim Crow South? with a response by /u/Dubstripsquads