"The valley is mentioned several times in the Old Testament, first in Joshua 15:8, where it is called "the valley of the son of Hinnom", which in Hebrew is gei ben Hinnom. We don't know who Hinnom was, but his son apparently owned the valley at one point. A later reference calls it instead Hinnom's own valley—that is, in gei-hinnom. Later, that term, gehinnom, came to be Gehenna. It is normally identified as the ravine southwest of Old Jerusalem."