If you read the Book of Kings, the nations with which Israel (or later, Judah and Israel) was always either warring or allying themselves are basically its neighbors: Egypt, Lebanon ("Tyre"), Syria ("Aram-Damesek"), Edom was in modern-day Eilat; Amon and Moab were in present-day Jordan.
In fact, the narrator (traditionally believed to be Jeremiah looking back after the destruction) tells us that King Solomon "dominated everything on his side of the Euphrates." Which is a sinister foreshadowing that the downfall will come from the other side of the Euphrates.
Only near the tail end of the North Kingdom does Assyria show up as an entity to be reckoned with; and only at the tail end of the South Kingdom, after that, does Babylonia show up -- both in modern-day Iraq.
What changed that made faraway armies a threat? Was there a shift in their civilization? Technology? Leaders who decided to go further afield?