The Valley of Salt is a region bordering Edom in the southeast of Israel. Its exact location is unknown. David and Abishai fought against Edom here.
2 Sam 8:13And David made a name for himself when he returned from striking down eighteen thousand Edomites in the Valley of Salt.
1 Chr 18:12Abishai son of Zeruiah struck down eighteen thousand Edomites in the Valley of Salt.
Later, during the time of Amaziah (King of Judah), Edom was fought against once more.
2 Kgs 14:7Amaziah killed ten thousand Edomites in the Valley of Salt and captured Sela in battle, calling it Joktheel, a name it has to this day.
2 Chr 25:11Amaziah took courage and led his people to the Valley of Salt, where he killed ten thousand men of Seir.2 Chr 25:12The men of Judah also captured ten thousand alive and took them to the top of a cliff and threw them down, so that all of them were dashed to pieces.