This amazing field-photo comes from an old postcard. Unfortunately, the only contextual information available is the title of the picture: ‘Sur les rives de l’Ubangi’. So, if a reader knows which Ubangian people these two lovely girls originate from, be sure to get in touch.
UPDATE: I finaly found the origin of this picture, see here. These two Sango girls were photographed by Meulemans ca. 1890 in Banzyville.