Hastings' Dictionary of the Bible (1898)
HIN'NOM, a valley to the south and west of Jerusalem, called also "the valley of the son," or "children, of Hinnom," or "valley of the children of groaning," a deep and narrow ravine with steep, rocky sides separating Mount Zion to the north from the "hill of evil counsel," and the sloping rocky plateau of the "plain of Rephaim" to the south. The south-eastern portion of the valley was called Tophet, or "place of fire," Jer 7:31; 2 Kgs 23:10, and the "valley of slaughter," Jer 7:32; Jer 19:6.
The earliest mention of the Valley of Hinnom is in Josh 15:8; Josh 18:16, where the boundary-line between the tribes of Judah and Benjamin is described as passing along the bed of the ravine. On the southern brow, overlooking the valley at its eastern extremity, Solomon erected high places for Molech, 1 Kgs 11:7, whose horrid rites were revived from time to time in the same vicinity by the later idolatrous kings.
Ahaz and Manasseh made their children "pass through the fire" in this valley, 2 Kgs 16:3; 2 Chr 28:3; 2 Chr 33:6, and the fiendish custom of infant sacrifice to the fire-gods seems to have been kept up in Tophet. To put an end to these sacrifices, Josiah polluted the place by spreading over it human bones and other corruptions, 2 Kgs 23:10, 2 Kgs 23:13-14; 2 Chr 34:4-5, from which time it appears to have become the common cesspool of the city, into which its sewage was conducted, to be carried off by the waters of the Kedron.
From its ceremonial defilement, and from the detested and abominable fire of Molech, if not from the supposed ever-burning funeral piles, the later Jews applied the name of this valley, Ge Hinnom, Gehenna, to denote the place of eternal torment. In this sense the word is used in the Gospels. Matt 6:29; Ezr 10:28; Matt 23:15;Mark 9:43; Luke 12:5. It is now Wadi Rababeh. The valley has usually been described as beginning at the north-west of Jerusalem and extending south 1 1/4 miles, turns east between Zion and the hill of evil counsel, passing through a deep gorge and joining the Kedron.
" Warren, however, identifies Hinnom with the Kedron valley east of Jerusalem (Recovery of Jerusalem, p. ,p. 14). Prof. Socin in Baedeker's Handbook, 1876 dissents from this location, and holds to the former identification of Hinnom.