In "By the Waters of Babylon," what is the son doing that is forbidden

The north and the west and the south are good hunting ground, but it is forbidden to go east. It is forbidden to go to any of the Dead Places except to search for metal, and then he who touches the metal must be a priest or the son of a priest. Afterward, both the man and the metal must be purified. These are the rules and the laws; they are well made.