Joshua 18:16
And the border came down to the end of the mountain that lieth before the valley of the son of Hinnom, and which is in the valley of the giants on the north, and descended to the valley of Hinnom, to the side of Jebusi on the south, and descended to En-rogel,
Joshua 18:16 belongs to the description of tribal boundaries set out in the division and settlement of the Promised Land, the conquered land of Canaan among Israel. That division followed the judgment on Achan's sin and the conquering of the Canaanites. The verse records part of the boundary description in the written account of how the land was divided among the tribes, a distribution section resting on documents that accurately described the properties. It marks part of the boundary of Benjamin's inheritance and lot, which lay adjoining Judah's territory, with Jerusalem lying within Benjamin's territory. It means the border came down to the end of the mountain before the valley of the son of Hinnom by the valley of the giants on the north, descended to the valley of Hinnom by the side of Jebusi on the south, and descended to En-rogel.
The Valley of Hinnom is likewise understood as a landmark in the boundary of Judah, south of Jerusalem. The verse is one of the Old Testament verses naming that valley, containing the Hebrew Ge Hinnom, also called Ben Hinnom. It is among the first biblical mentions of that valley, which lies near Jerusalem on the south, bordering Jerusalem below Mount Zion, and is named in the description of a territorial boundary. Hinnom was an otherwise unknown person whose name was given to the valley. The name Gehenna is the Greek spelling and form of the Hebrew name for this valley, the valley of the son of Hinnom, from which the word rendered hell comes, and its rendering in the Septuagint as Gai-Ennom in some copies and Gaienna in others proves the derivation of the New Testament word gehenna from the valley of Hinnom.
The valley is often mentioned in connection with the horrid rites of Molech or Moloch celebrated there under idolatrous kings, including idolatrous sacrifice and child sacrifice. After Josiah overthrew and suppressed that idolatry, he defiled the valley with bones of the dead. It then became the common refuse place and refuse dump of Jerusalem where combustible refuse was consumed and burned by fire, a history as a place of idolatrous sacrifice and desecration that explains its association with filth, dead bodies, fires and worms, and it is called the Valley of Slaughter in Jeremiah. Hence it became a type of hell, the gehenna of the New Testament being no other than this Valley of Hinnom, the place of future punishment. The verse therefore refers to a geographical valley, not to a place where the wicked are punished after death.