This mandala is used as a teaching device to illustrate some important ideas in Buddhism, particularly having to do with karma and rebirth.  It is a valuable tool for psychological introspection as well.  No one knows for sure when it was first devised, but some believe it goes back to the time of the Buddha himself (2500 years ago).   For a very good explanation of the meaning of this wheel  right-click your  mouse on  Rebirth-Wheel.