of the desert. he spent more time there, much of it alone, than just about anyone. >> anthony: the bedouin have been questing the empty quarter hundreds of years, thousands of years? >> ahmed: thousands of years. the bedouin are the kings of the desert, it's their place it's their area. they know how to live and they know how to suffer. >> anthony: mark evans, a polar and desert expedition leader knows firsthand how difficult the empty quarter can be. guided by amer and accompanied by colleague mohammed al zedjali he recently made the crossing, walking over 600 miles with camels in tow. >> mark: in the first 12 days of our journey crossing the empty quarter, we didn't touch our own food at all. and it became a competition to be more generous than the previous -- >> anthony: so you meet people out there all along the way? >> mark: you would, even though nobody lived there people would find you and travel.