Introduction to the discovery of the Daxi ruins: In the 1820s, some foreign missionaries and explorers from far away went deep into the Three Gorges area of ​​the Yangtze River to conduct inspections and explorations. Among them, a "Central Asian expedition" led by American Nelson took the lead in collecting some stone tools and pottery shards at the east entrance of Qutang Gorge, and discovered the Daxi ruins for the first time.