You suspect that Israel had already taken off?
There is no historical record of anyone 'taking off' anywhere.
The descendent's of those tribes were there when both the Babylonians and later the Persian took over that area.
History is about facts not conjecture based on zero evidence.
Moreover, you had asked me for proof that the Babylonians had indeed destroyed the Assyrian Empire.
That historical event does have actual evidence to support it.
They weren't mentioned as taking part of the sacking of the Assyrian capital.
The descendent's of those tribes were there when both the Babylonians and later the Persian took over that area.
You dispute that The combined armies of Nabopolassar and Medes destroyed Nineveh?
This is information from the Assyrians own records, which have all been translated. Perhaps your history writers neglected the thousands of tablets in the British museum.
This is resource you seem to be lacking.
However, there is little to been read of the Israelite save Assyrian writings because, as you pointed out, God intended for them to forget their heritage.
Do you see the implications of that regarding your argument?
History is about facts not conjecture based on zero evidence.
None of your history mentions the Israelite tribes and their placement in Assyria. They were definitely there.