quite possible for Mr. Thomas and Mr. Philby each to find Wabar in an opposite corner of Arabia." The Shisr discoveries Nicholas Clapp's search for Ubar began after he read Thomas' book Arabia Felix. Clapp had just returned from Oman, having helped to stock an oryx sanctuary on the Jiddat al Harassis, and was inspired by Thomas' references to the lost city of Ubar. He began his search for Ubar in the library of the University of California in Los Angeles, and found a 2nd-century AD map by the Alexandrian geographer Claudius Ptolemy which showed a place called "Omanum Emporium". He speculated that this might be the location of Ubar, situated on the incense route between Dhofar and the Mediterranean region. Aware that Mayan remains had been identified from aerial photographs, Clapp contacted NASA's Jet Propulsion Laboratory and obtained satellite images of Dhofar. These helped to identify ancient camel tracks hidden beneath the shifting sands of the desert which in turn might identify places of convergence such as wells and ancient cities. After Clapp's team had visited a number of possible sites for Ubar, they found themselves drawn back to the crumbling ruin at Shisr. Although the fort had been written off as being no more than a few hundred years old by the earlier explorers, Clapp's team began to speculate that the fort had been rebuilt in the 1500s on the remains of a far more ancient site. Under the direction of Juris Zarins, the team began excavation, and within weeks had unearthed the wall and towers of a fortress dating back more than 2,000 years. Clapp suggested that the evidence was "a convincing match" for the legendary lost city of Ubar. The city's destruction, he postulated, happened between A.D. 300 and 500 as the result of an earthquake which precipitated the collapse of the limestone table; but it was the decline of the incense trade, which led to the decline of the caravan routes through Shisr, that sealed Ubar's fate. Zarins himself concluded that Shisr did not represent a city called Ubar. In a 1996 interview on the subject of Ubar, he said: In a more recent paper he suggested that modern Habarut may be the site of Ubar. By 2007, following further research and excavation, their findings could be summarised as follows: A long period of widespread trade through the area of Shisr was indicated by artefacts