The "religious ceremony" and "woman in Pleiku" photographs

The two photographs appear to be taken of the same place at the same time, as the man at the drum seems to be the same person.

Whatever is to the right of the "woman in Pleiku" would tell us for sure what the "ceremony" consists of.  Without that, I cannot be certain, but I am fairly sure that the photographs capture a corner of a "seance," where a woman (or a feminized man) came into contact with dead people.  That person is called the "-do^`ng".  The photographs captured the musicians who assisted the DONG.

It's the music that supposedly placed the DONG into a trance, thus allowing the spirit of the dead to enter the body of the DONG and speak through her.