The Kalmakov picture becomes more interesting. If painted in 1913, perhaps there is a connection to Mir Iskusstva and the Ballets Russes. That could also explain why Sadko is in Arabian costume (Ballets Russes produced Sheherezade a few years before "Death" was painted). I found these costumes designed by N Goncharova for the Ballets Russes production of Sadko - for the character of the Sea Princess (perhaps the dancing figure in the Kalmakov painting is the Sea Princess?) and the Sea King for the same ballet:
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Now the hat on the "Death" figure could simply be a submarine-shell crown. But there is another costume for the Ballets Russes production of Prince Igor (this time by Bakst) with a cone-like crown. Just for fun I include two images with similar cone-headgear:
Finally, if the Kalmakov figure of Sadko is not Sadko, but some character from the Arabian Nights, here is Nijinsky as a joyful slave in a costume designed by Bakst for Sheherezade: