(IDEX Online) - A legendary Cartier watch - one of only four ever made - could fetch $400,000 when it is auctioned at Sotheby's Paris next month.It was presented to Belgian motocross driver Gaston Rahier for a unique achievement, winning his class of the grueling Paris-Dakar Rally across the Sahara Desert in both 1984 and 1985.The Cartier Cheich (pictured) has a dial framed by a gold 'cheich' design, inspired by the cloth worn around the head by the Tuareg people of the Sahara to protect them from the sun.The watch is being offered by relatives of Rahier, who died in 2005.Two of the other Cheich watches were retained by Cartier. The fourth was presented to Thierry Sabine, founder of the race, but is now considered lost. He and four others died in a helicopter crash in Mali in 1986."There are so many reasons why the Cartier Cheich watch is extraordinary," said Beno?? (R)t Colson, international watch specialist at Sotheby's."It is hard to just pick one. As a true horological masterpiece, and for its association with the triumph and tragedy of the legendary Cartier Challenge, it has achieved near mythical status and the market has been longingly waiting for its first appearance at auction." Estimate: $200,000 to $400,000.