The Two Houses: Judah, Israel, And The Restoration Of The Whole Hebrew Nation

After Babylon falls to Persia, Cyrus permits return and rebuilding. The return
and Second Temple frame are largely Judean and Jerusalem-centered.

This helps explain why Judah/Judea/Jew becomes the visible public identity. The
people tied to Judah and Judea are the visible surviving covenant witness in the
historical record after exile and return.

But visibility is not the same as totality.

That is the key sentence for this study:

Judah became the visible public survivor, but the prophets still speak of the
whole house.