The pits are spread out within a 7,000-square-meter area in Qiannanzhuang village, where the locals used to obtain their millstones 600 years ago. /VCG Photo

The millstones were initially made to grind rice and beans for daily use, and to sell to neighboring villages. /VCG Photo

The local history of producing millstones lasted for centuries, but since the 1950s they have been gradually replaced by machines. /VCG Photo