🔼The name Shihor in the Bible
When Joshua had become old, YHWH spoke to him and informed him rather redundantly that there was still much of Canaan that wasn't conquered, from the Shihor eastward (Joshua 13:3). But the tribes all had their territories assigned to them, and as soon as Joshua passed away, the federation spiraled into the throes of multi-lateral civil war, and lost all motivation to conquer the remaining parts of the promised land.
Still they managed to somehow settle near the Shihor, because when king David wanted to transport the Ark of the Covenant from the house of Abinadab at Kiriath-jearim to Jerusalem, he "gathered all of Israel from the Shihor of Egypt to the gate of Hamath" (1 Chronicles 13:5).
Much later, the prophet Isaiah speaks of the grain of the Shihor, which was the revenue of Tyre (Isaiah 23:3). And in light of the various deportations and places of refuge, the prophet Jeremiah taunts, "Why are you going to Egypt? To drink the water of the Shihor? Or why are you going to Assyria? To drink from the Euphrates?"
🔼Etymology of the name Shihor
The name Shihor looks like it comes from either of the two root-verbs שחר, although most commentators seem to prefer שחר I (shahar I), meaning to be black:
For a meaning of the name Shihor, NOBSE Study Bible Name List reads Black, Turbid and Jones' Dictionary of Old Testament Proper Names has Very Black, Turbid.
BDB Theological Dictionary doesn't list the name Shihor under either root שחר but in its alphabetical spot. BDB grimly adds: "usually derived from שחר I as black water, but doubtful". Why this would be doubtful BDB doesn't say, but it's equally doubtful that a Hebrew audience would concur with BDB's technical objections. Reading "black water" into the name Shihor is probably folk-etymology, but that's what counts in any highly symbolic narrative.