1 Kings 4:1

So king Solomon was king over all Israel.

Solomon became king over all Israel after the death of David, having already been anointed and proclaimed king in the closing years of David's life when David gave up the throne in his favor. He reigned from Jerusalem after returning there from Gibeon and worshiping before the ark. This was the time when Israel reached the height of her greatness under the reigns of David and Solomon, when Judah and Israel had become many in multitude as the sand by the sea. His rule was to be established and Israel exalted among the nations as a wise and understanding people if he walked uprightly before God and obeyed all His commands.