Bushiri bin Salim al Harthi arrested and chained by Askari on December 5 1889 in Pangani, he was the leader of the Arab revolt against the Germans. Bushiri's pistol is in the belt of one of the Ashkari.
This photo probably was taken by Etienne Baur as Bushiri was more or less a friend. Baur played a key role in The negotiations between the Germans and the revolting Arabs. For many details see ref 2.
The photo on the left with Buschiri's arrest was also used for ref 3.
Bushiri arrested and chained in Pagani December 16 1889