The Mongolian Expanse is a vast region of Central Asia that includes the Gobi Desert, which is a 4-letter word, and the Gobidesert, which is a 10-letter word. The Gobi Desert is a large desert in northern China and southern Mongolia, while the Gobidesert is a large desert in western Mongolia. Both deserts are part of the Mongolian Expanse, which is a large area of steppes, mountains, and deserts.