How deep should the buried grave be dug?

The depth and width of the tomb are very particular, and the feudal era has strict regulations on the depth of the tomb. According to geomantic omen, ordinary people in modern society have no children, three feet nine, one son, more than four feet two children and four feet seven. Theoretically speaking, the nobler, the more children and the deeper the tomb, so the imperial tomb is buried deeply. But six feet is the limit for ordinary people.