The archaic poems, Deuteronomy 33:2, Judges 5:4-5, Habakkuk 3:3, agree: YHWH comes from Sinai, Seir, Paran, Teman, the Edomite-Midianite south. The oldest extrabiblical attestation is the Egyptian Soleb inscription of Amenhotep III (c. 1400 BCE), naming 'the Shasu of YHW(H)' among southern nomads. At Timna, in the Arabah copper mines, a Midianite-period shrine (13th-12th century BCE) yielded a copper serpent and tent-sanctuary remains. The Kenite-Midianite hypothesis, that Israel adopted YHWH from southern metalworking tribes, is the scholarly frame, argued from these texts, not from fringe literature.
The folk discomfort is real: Israel's God arriving from outside Israel reads, to many, as an invasion narrative in reverse. The biblical text itself never hides it, Moses meets YHWH at a Midianite mountain and marries into a Midianite priest's family (Exodus 2-3, 18), Jethro teaches him administration. The adoption story is in the opening books.
The southern dossier has a consistent texture: volcanic fire imagery, copper mines, a serpent idol, smith-nomads whose god rides storm clouds. Whether or not the Kenite hypothesis is right in full, the oldest YHWH is documented as a god of fire, metal, and desert storms, a theology smelted before it was written.
If the God of Israel is documented first outside Israel, whose god was he?