From The Borders of Pandora

The Vault is rumored to contain the peak of all power. In past legends, theories have contained the wildest of ideas. Some have stated that he who opens the vault will be greeted by the guardians of Pandora, and given a godly position among their counsel. Others have said that the one who succeeds will find an abundance of treasure and given sovereignty over all regions of Pandora. But who can say? Its never been documented. Only idealized. Every 200 years the Vault is at its most vulnerable. If certain steps are followed, it can be opened.
For centuries families have been raising their children to withstand great challenges. Training them to become Vault Hunters. They teach them to believe that the only goal that truly matters is fulfilling that legacy. Though they all fail eventually. No one has succeeded. And some think no one ever will.