Introduction to Longcheng Yadan: Longcheng Yadan is one of the three largest Yadan groups in the Lop Nur area, located on the north shore of Lop Nur. The Tutai Group looks like a swimming dragon from a distance, so it is called Dragon City. Longcheng Yadan is also known as Bailongdui Yadan, and was selected as the second among the three most beautiful Yadan in China by "China National Geographic". It is also known as "the most mysterious Yadan" because few people have seen it. True appearance.