Surrounded by Mingsha Mountain, a crescent-shaped spring lies in the green basin, hence comes the name Yueya Spring (Crescent Spring).   

The Crescent Spring is located at the north foot of Mingsha Mountain, about 50 meters from north to south and 5 meters deep on an average. It is so named because it shapes like a crescent. The Crescent Spring water is sweet and crystal clear, and never gets covered up by drift sand. It never overflows after long-lasting rain or dries up after a long drought. It has wonderful scenery, with flickering leaves of aspens and weeping willows, sweet flowers of narrow-leaved oleaster, swaying reeds and hovering wide birds.    

A group of buildings stands on the south bank of the Crescent Spring, including the Niangniang Temple (Goddess Temple), Longwang Palace (Dragon King Palace), Yaowang (the God of Medicine) Cave, Yuquan (jade spring) Building and Leiyin (sound of thunder) Temple. Groups of fish swim in the Crescent Spring. Legend has it that there is a kind of fish called Iron Back Fish can cure all diseases and a kind of grass called Seven-star Grass can nourish yin and strengthen yang (yin and yang, the two opposing principles in nature, the former feminine and negative and the latter masculine and positive). People who eat iron back fish and seven-star grass can live forever and never grow old. Therefore, the Crescent Spring is also known as the Medicinal Spring.

Repeated recordation of the Crescent Spring can be found in historical documents, closely connected with the Mingsha Mountain. According to historical records, the marvelous desert spectacle of Mingsha Mountain and the Crescent Spring has a history of more than two thousand years. Over all these years, people never foud out why drift sand did not fill the spring.

According to research, the Crescent Spring is embraced by sandy mountains on all sides, with the mountain ridges turning into a crescent shape as that of the spring. Wind blowing into such circular valley will spiral upwards according to aeromechanics principle. As the result, sand drifted down from one side of the mountain will be carried to the opposite side by wind. That's why sand never fills the spring. Owing to such a unique terrain movement, the sandy mountain and the spring keep a contradictory as well as a harmonious coexistent relationship with each other over two thousand years.

Reputed as the first desert spring under heaven, the crystal clear Crescent Spring is one of the eight sights in Dunhuang. It is also a national key point of interest, ranking among one of the forty famous scenic spots in China.