In southern Oman and Saudi Arabia lies an area of such formidable desert that it is known as the Rub Al-Khali or 'Empty Quarter'. Wilfred Thesinger, an avid explorer and ethnographer criss-crossed this region in the 1940s and spent years in an area where few outsiders dared to tread. The feat was not attempted again until Bruce Kirby and two other Canadians cleared a mountain of bureaucratic red tape and crossed in 1999 with their Bedouin guides and trusted camels. Kirby described the adventure in his book "Sand Dance".
For a little more background on Thesinger's footsteps, please see my friend Louis' blog.
http://louisliew.blogspot.com/2007/03/musings-from-muscat_7593.html