They were born Robert LeRoy Parker and Harry Alonzo Longabaugh respectively. One picked up his nickname after working as a butcher and the other after serving an 18-month jail term for robbery in Sundance, Wyoming.

And their tale went on to be adapted for the 1969 box office smash, Butch Cassidy and the Sundance Kid, starring Paul Newman and Robert Redford, which turned the tale of the Wild Bunch outlaws who fled to South America with USDollars 1,000 rewards on their heads into the stuff of legend.

With 2006 marking the 100th anniversary of Butch and Sundance's arrival in Bolivia and a fledgling backpacker trail already carving out a route in their footsteps, interest in the legend of Butch and Sundance is fuelling a new boom in Bolivia for Butch Cassidy tours.

"Bolivia's Tupiza region is as captivating today to backpackers as it was to Butch and Sundance a century ago, while the story of Butch and Sundance's misadventures in the Tupiza region is attracting increasing numbers of tourists, history buffs and trekkers," says historian Ann Meadows, author of Digging Up Butch and Sundance, the definitive book about the outlaws.