Minfeng County, Hotan Prefecture, Xinjiang Uygur Autonomous Region. Wang Yucheng/CGTN

The Niya Ruins are located in a desert, 150 kilometers north of Minfeng County. Wang Yucheng/CGTN

Niya was once a major commercial center on an oasis along the Silk Road in the southern Taklamakan Desert. Wang Yucheng/CGTN

In ancient times, camel caravans would cut through the desert, carrying goods from China to Central Asia. Wang Yucheng/CGTN

The ruins covers an area of 220 square kilometers with traces of canals and river courses. Wang Yucheng/CGTN

According to the "Book of Han," this city had some 500 households with about 3,360 residents. It once belonged to the Kingdom of Jingjue. Wang Yucheng/CGTN

Researchers have found well-preserved tools in the ruins, such as iron axes and sickles, wooden clubs, pottery urns and jars of preserved crops. Wang Yucheng/CGTN

Niya's residents left for reasons still unknown to scholars, and the sand slowly buried the city. The great mystery is still waiting for somebody to unlock. Wang Yucheng/CGTN