The back of this photo is rubber-stamped with "COPYRIGHT REGISTERED BY PHOTO DROSSOPULOS DAR-ES-SALAAM." There is no other information, no place-names, no dates. I assume that the photo was taken in 1930, only because it seems to fit my grandparents trajectory from Europe to Congo. The name "Drossopulos" is correctly spelled. I didn't find anything on the Web about this photographer, although there was a G. Drossopoulos operating in Lubumbashi (Elisabethville).
<a href="//commons.wikimedia.org/wiki/User:Nicolas_G._Mertens" title="User:Nicolas G. Mertens">Nicolas G. Mertens</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>