Was the land promise to Israel already fulfilled in the Old Testament?

The Old Testament actually declares the land promise fulfilled — three separate times, using identical language — and then the New Testament expands what the promise was always pointing toward.

Three narrators in the Old Testament, recording accomplished history rather than speculating about the future, use the same phrase to declare God's word kept. Joshua 21:43, 45 puts it plainly:

"YHWH gave to Israel all the land... Not one word fell from all the good word... All of it came to pass."

That phrase lo' nafal davar (לֹא נָפַל דָּבָר, "not one word fell," H5307 + H1697) is a comprehensive fulfillment declaration. Four hundred years later, Solomon uses the same formula at the temple dedication: "Not one word has fallen from all his good word that he spoke through Moses his servant" (1 Kgs 8:56). Then Nehemiah's Levites, writing from the post-exilic perspective, look back and affirm: "The children came in and possessed the land" (Neh 9:24). Three independent witnesses, spanning centuries, saying the same thing.

But the text doesn't stop there, and this is where it gets interesting. Hebrews 11:13–16 says the patriarchs "died in faith, not having received the promises" — and that they were looking for "a better country, that is, a heavenly one." The immediate, territorial dimension was fulfilled under Joshua. But Abraham himself, according to Hebrews, understood the land was pointing somewhere further. Paul makes the same move in Romans 4:13: the promise to Abraham was that "he would be heir of the world" (klēronomon tou kosmou, κληρονόμον τοῦ κόσμου) — not heir of Canaan. The same inheritance vocabulary the Greek Old Testament uses for the tribal land allotments in Joshua 18–21 gets applied by Paul to the whole cosmos.

The pattern is fulfillment, then transformation: physically fulfilled under Joshua, eschatologically expanded toward the new creation. Both things are true, and the text says both.

For the full Hebrew text and the olive tree argument, see the study on the Abrahamic covenant, section "The Land Promise: Fulfilled, Then Transformed."