Because of course, if you're a victorian artist you only have 3 excuses for painting raunchy nudes: The subject can be historical/mythological. The subject can be allegorical. Or the subject can be Foreign.
Hence a whole load of "slave-market" and "harem" scenes which would have been hung in the most repectable art galleries for public edification but were in fact quite gloriously dirty. BDSM in early guise, in many cases. Huzzah!
This one from 1866 is called "Slave Market" or sometimes "For Sale" and is by Jean-Leon Gerome. (Lots of his pictures here in high definition.)