en_tn/jdg/21/01.md

Now the men of Israel had made a promise ... marry a Benjamite."

This background information tells the reader about the promise that the Israelites made before the battle with the Benjamites. (See: rc://en/ta/man/translate/writing-background)

Benjamite

This is the name of the descendants of Benjamin. See how you translated this in Judges 3:15.

Why, Yahweh, God of Israel, has this happened to Israel, that one of our tribes should be missing today?

The people of Israel used this rhetorical question to express their deep sadness. This question can be translated as a statement. AT: "Oh Yahweh, we are so sad that one of the tribes of Israel has been completely destroyed." (See: rc://en/ta/man/translate/figs-rquestion)