The Tengri Deserts (Badain Jaran, Tengger, and Kubuqi are the three most famous) are located at the border between Alashan League and Gansu Province. Surrounded by Helan Mountains in the east, the Great Wall in the south, Abrai Mountains in the west, the deserts cover 14,170 square miles and are about 2,000 feet above sea level, making them among the coldest deserts on the planet. The area is an archeologist's mecca: Dinosaur eggs and fossils, stone tools and other uten­sils, and a recently discovered 7,000-year-old stonemason's workshop have been found here. It is believed that more than 4,000 years ago this area was once fertile farmland.