Civilization: Starting from Manzi Cave

History textbooks say that Chinese civilization is well documented and dates back to five thousand years. Santai County in northwest Sichuan has many hilly and forest areas, with hills less than 500 meters above sea level. Many hills are connected to relatively flat hills, about 20 to 50 meters above the ground. The largest ones are several miles in radius, while the smaller ones are just dozens of acres of land. There is such a place in the author's hometown, behind the town middle school. There will be many barbarian caves in this kind of place, which are on a large scale. I think they are an unknown civilization in prehistoric times.