Rogues, vagabonds, and wandering poets... characters from D&D or perhaps a videogame? In the medieval underworld of the Islamic Middle East, these shady characters made up the Banu Sasan, "a hidden counterpoint to the surface glories of Islam’s golden age." Mike Dash has the feature article for Smithsonian's Past Imperfect blog.
In this sense, of course, the Banu Sasan were merely the Middle Eastern equivalents of rogues who have always existed in every culture and under the banner of every religion; Christian Europe had equivalents enough, as Chaucer’s Pardoner can testify. Yet the criminals produced by medieval Islam seem to have been especially resourceful and ingenious.
Ismail El Outamani suggests that this was because the Banu Sasan were a product of an urbanization that was all but unknown west of Constantinople at this time. The Abbasid caliphate’s capital, Baghdad, had a population that peaked at perhaps half a million in the days of Haroun al-Rashid (c.763-809), the sultan depicted in the Thousand and One Nights–large and wealthy enough to offer crooks the sort of wide variety of opportunities that encouraged specialization. But membership of the fraternity was defined by custom as much as it was by criminal inclination; poets, El Outmani reminds us, literally and legally became rogues whenever a patron dispensed with their services.