The four Nabatean towns of Haluza, Mamshit, Avdat and Shivta, along with associated fortresses and agricultural landscapes in the Negev Desert, are spread along routes linking them to the Mediterranean end of the incense and spice route. Together they reflect the hugely profitable trade in frankincense and myrrh from south Arabia to the Mediterranean, which flourished from the 3rd century BC until the 2nd century AD. With the vestiges of their sophisticated irrigation systems, urban constructions, forts and caravanserai, they bear witness to the way in which the harsh desert was settled for trade and agriculture.