Dunhuang Yadan national geological park is away from Dunhuang about 165 kilometers, located at the junction of Gansu and Xinjiang and close to Lop Nor(nuclear testing site in Xinjiang) . According to preliminary estimates, the Yadan landform of dunhuang is 20 kilometers both in length and width, with a total area of about 400 square kilometers .The average time of formation was between 700,000 to 300,000 years ago.