The Gobi Desert is a large desert and semi-desert region in East Asia, spanning parts of northern China and southern Mongolia. Unlike many deserts that are entirely sandy, much of the Gobi is composed of bare rock and gravel plains. It is a rain shadow desert, formed because the Himalayan mountain range blocks rain-carrying clouds from the Indian Ocean. The Gobi is a cold desert, and it is common to see frost and occasionally snow on its dunes. Historically, it was a significant part of the Mongol Empire and home to several important cities along the Silk Road. Paleontologists also recognize the Gobi as one of the world's most productive fossil sites; in the 1920s, the first dinosaur eggs were discovered here at the Flaming Cliffs, revolutionizing our understanding of prehistoric life.