An Arab city of the early medieval period. Urban centers in the Middle East were of a size and wealth all but unknown in the Christian west during this period, encouraging the development of a large and diverse fraternity of criminals. From a contemporary manuscript.
The year is—let us say—1170, and you are the leader of a city watch in medieval Persia. Patrolling the dangerous alleyways in the small hours of the morning, you and your men chance upon two or three shady-looking characters loitering outside the home of a wealthy merchant. Suspecting that you have stumbled across a gang of housebreakers, you order them searched. From various hidden pockets in the suspects’ robes, your men produce a candle, a crowbar, stale bread, an iron spike, a drill, a bag of sand—and a live tortoise.
The reptile is, of course, the clincher. There are a hundred and one reasons why an honest man might be carrying a crowbar and a drill at three in the morning, but only a gang of experienced burglars would be abroad at such an hour equipped with a tortoise. It was a vital tool in the Persian criminals’ armory, used—after the iron spike had made a breach in a victim’s dried-mud wall—to explore the property’s interior.
For the rest of the story: http://blogs.smithsonianmag.com/history/2013/07/islams-medieval-underworld/