The Gobi Desert was a desert in China and Mongolia.
When the First Doctor, Susan, Ian and Barbara met Marco Polo in the 13th century, they travelled across it on their way to the Imperial Palace in Peking. (TV: Marco Polo)
In the 21st century, UNIT Lieutenant Sam Bishop and Petronella Osgood were deployed to the Gobi Desert in Mongolia in search of a Nestene energy unit. (AUDIO: Earthfall)